I did several searchs and people have said no its a lie, yes its a lie, no its not true you need one, yes its true but you need a hole in it, no its not true but having one with a hole it is true or....

I want the truth darnit!

 

From what I understand, no thermostat would allow coolant to flow through the engine at all times during running... this is not good b/c the coolant has little to no time to cool down inside the radiator.

 

from my understandeing is that all it does it block off the water goign into the motor till the motor get to running temp then it opens and from there its free flowing cuz its always open till the motor cools off (180 for most aftermartket temos) so if you remove it all it will do is not warm up as fast. that my understandeing on it. and i'm pretty sure its true but i could be wrong.....lets see what other people have to say

 

I ran my old ford for a while with no thermostat and it overheated big time, I think you need the restriction to slow down the coolant so it has time to cool off in the rad. Im guessing on this one but I know it didnt overheat anymore with a thermo.

 

what alot of red necks do is put a 5/8s washer in there to slow the flow down.. this allows coolent to keem moving and it slow down the flow so it can cool in the radiator>

 

Well - it appears some restriction of coolant travel is necessary. Whatever you do, make you do something to regulate the flow (a stat, the washer trick, etc)... don't just take it out!

 

just put a clamp on the house LoL

 

I seem to get a lot of that "it needs to slow down so it can cool off in the rad" from people.

I've been doing some research on that, and it seems like everyone that thinks that was just told by somone else...

If slowing it down cools it off then why does a thermostate open up to cool it off? that sounds like reverse engineering the design of the water pump in the first place.

If slowing it down made it cooler, then why buy high flow water pumps? we want it to flow slow, not fast right?

Everything I've read so far indicates the faster the water flows, the better. if you want it to get hotter then you slow it down, so it has more time to heat up in the engine.

I just dont see how a restriction can help it stay cooler. Im going to do more research and come back...

 

Forget everything you just read here and listen to the other guys who are speaking the truth The water needs to stay in the radiator long enough for the radiator to do it's job. Just remember 1 thing if you forget everything else, the manufacturers don't care how they sell it to you as long as you will buy it. Some things do exactly what they are intended to do...take the money from your pocket and put it in theirs

 

IMO 99 percent of the time it will run cooler without the stat if the cooling system has the ability to run cooler. If you are running a 180 stat and it won't stay below 220--removing the stat won't help much. The radiator provides plenty of restriction all by itself. That being said, keeping the coolant a constant temp is important too. Also, running a thermostat has no bad side effects.

 

Let me put my 2 cents in. I work at a coal fired power plant and have to deal with thermal dynamics all day, but I am not expert either. With that said the cooling system in any car is engineered to run at a certain temperature range. If you wish to modify it to run at a lower temperature then altering one component wont have the desired effect.
Here is the scoop:
If you change the thermostat or remove it then the cooling medium(coolant) will flow faster through the engine. This also increases the speed of the coolant through the radiator. The radiator as I said before is designed for a specific flow rate. To get the coolant to cool more in the radiator you will have to increase the radiator's cooling medium(air) to cool the coolant flowing through it, or increase the surface area of the radiator(bigger radiator). If the coolant flow through the engine is increased and a factory radiator is used then the radiator's outlet temperature will be higher because the dwell time (time the cooled fluid spends in heat exchanger) has been reduced.
Now the deal with a higher flowing pump. The higher flow pump will not only increase system pressure but also increase the coolant flow throught the engine and radiator, but to achieve good results you will need the bigger radiator an higher flowing fan(s).
This is a balancing act that by just changing one component will not achieve the desired results.

-Ozzy

 

Ozzy88GTA has got it right. From my own experience I changed the thermostat to a 160 then I went to high performance fan and water pump which all helped but the stock radiator just couldn't handle the extra pressure and so I put a Griffin radiator in and now everything works great.. No more over heating and I can now put my ac back in the car.
cc82z-28

 

Don't get confused on what Ozzy88GTA said. When the water flow is increased through the radiator, the radiator water outlet temp will be higher. This does not mean that there is less heat taken away because the water comming out is a higher temp. Remember that the greater the difference temperature between two mediums the greater the rate of heat exchange.

 

hmmmm, i tried this once and my temp fluctuated from 200 ~ 190 w/ a new thermostat, to 185 and never budged without. weird. And yes, i did try a new thermostat thinking there was somwthing wrong with it. All these answers are scientific and all . However, if the slowing down coolant theory (or fact) was 100% true, than the temp of my engine shouldve increased. But it didnt, so i think theres more to it than that. my opinion, thats all. Weird nonetheless, and a very interesting coolant flow theory.

 

There is also the fact that coolant flow throught the engine is never constant unless you are on cruise control on flat road. Air temperature and vehicle speed are always changing too so there are always some variables that should be accounted for. And let's not forget about the condition of the cooling system.

 

Florida

355 w/ dual fans on all the time, stock rad etc, heater core by passed, w/ ******* washer/therm. and purple ice.

ran cool all the time, needle never moved from the temp it was when i started it. drive all over, stop and could touch valve covers, w/ uncoated hooker lts.

but I hooked the heater core back up fer a trip to MI, ran ice cold on free way, stop in traffic it woulds raise real quick.

I let the car warm up one morning and blew a hose.

so heater core was a no-no in my case

 

Simply do it! I did, and guess what it don't get hot. Run her without a stat and it will never heat up. You can't move the water fast enough for it not to cool. It's a myth pure and simple. I ran the rock, and my Blazer when doing a flush without a stat. Guess what, the guage barely came off the stop when it was 80 degress outside. Dats 'da facts Jack!

 

no thermostat = runs cooler for me!! but i like having one in because it takes FOREVER to warm up.

 

<b>Run her without a stat and it will never heat up. You can't move the water fast enough for it not to cool. It's a myth pure and simple.</b>

So your saying its a myth...

<b>The water needs to stay in the radiator long enough for the radiator to do it's job.</b>

HE says its not a myth.


and there are a host of other people who say it is, and it isnt. Im still not sure what the heck is going on.

Let me ask this, I just put a thermostat in my intake (195*) and i noticed that when open it barelly moves much at all. does the water really flow that slow through it?
Also i noticied water cannot flow much at all without it open. doesnt this put pressure on the water pump or somthing?

 

I'm not a mechanical engineer, though it seems like you guys could use one around here.

I had the phenomenon explained to me once by an ME friend of mine. He's got a 95 K2500 with the 6.5TD (notorious for cooling problems), for reference.

Anyway, the problem with flow speed is simply that the fluid doesn't get cooled uniformly. That is, the outer edge of the flow radius gets cooled more than the inner area. That means the inner area isn't getting cooled because there isn't enough surface area in the rad. Ozzy88GTA was basically on the right path. If you increase coolant flow, you need to change other parameters, as well, or it won't work right.

So the answer for stock cooling systems and no stat is, try it and see! If your system always seemed to work efficiently with excess capacity, then most likely, the car will run with the temp needle pegged on cold. If the car has cooling issues, then it will probably overheat anyway.

Also, someone else mentioned something important - the amount of heat transfer at any given moment is directly proportional to the temperature delta between the two mediums...

 

I don't say it, my neighbor, motorcycle buddy and all around real life genius who IS a mechanical engineer,and who restores old Caddy's, and who's specialty is fluidics says so. There are so many myths about so many things that it's hard to find the truth. If you just changed a stat, why the hell don't you just leave it out and then try it. Case closed. Yes, water flow through the engine is slow as compared to nuclear power plant flow but it's irrevolant. Heat transfer occurs at an atomic level but of course with many variables, but the fact is that constant flow without the use of a stat causes the engine to run as cold as ambient air and transfer equipment permits. And, to the so called restrictor, well vary the rpm's and so much for restriction. In all honesty, and I am not trying to be sarcastic if I were you the first thing I would do is take out the stat. If the bastard overheats then I would come at me with a vengenace. It won't. So, either you are a time waster of which there are many, or you are too lazy to try it. Dude, it's you call.

 

I've tried it with and without a stat, and it overheats no matter what.

ive upgraded the water pump and radiator and got the dual fan setup from flex-a-lite. and it still overheats.

im experimenting with stats now, with holes, so yes im trying it all out.

 

Does anyone know the factory cfm rating for the original fan/fans? This would be good to post on this site to get an idea how well, or not so well, the flexlite stuff will work.

 

Yes you do need some restriction to create cycle time, its a well known fact by those who know and just plain common sence.

The coolant needs to slow down thats why all autmotive systems are designed with a thermostat to not only open at XXX* but to REGULATE THE FLOW of the coolant too. If you have no regulation the coolant will just flow through the system and eventually every drop will become the same temprature usually very hot. Same basic design as an air conditioning system. The low side is cold in the -* and the high side is well over 300*+. Although its a different system is does function in a similar way to the water cooling the engine instead of expansion valves and low pressure areas the engine uses a thermostate to create the same effect.

If someone removed the t-stat and it runs cold constantly either they dont drive very far or have a plugged radiator.

 

A plugged rad causes it to run cold? There was the exact discussion here some time ago and a guy who was a lot smarter than me gave a perfect explanation of why what you say is incorrect. The stat is not a restrictor as you state. It's ability to restrict flow is irrelovant because pump speed changes. Also it's not the opening so much as the thickness of the restrictor that really matters. The analogy to air conditioning is not a valid one because with AC you deal with the principal known as "latent heat of vaporization" as well as heat transfer. In a TG cooling system if it has no stat it don't get hot unless it idles enough for the cooling fan to come on. The last time this was discussed I took mine out and drove it for a week. It ran cold, got crappy fuel mileage and unless I sat at a light for several cycles the guage barely came off the stop. If what you say is true, how about when you drill holes in the stat as described here. You know what happens, when it comes up to temp the average operating temp is lower than the stat rating. Based on what you say it should be HIGHER since you eliminate restriction. I have done that too, the temp is LOWER than it was with the same stat before the holes were drilled. Like it or not thats what happened. I am not trying to belabor the point and I said this is not my area but I have in fact has this discussion with people who DO know and in a TG cooling system thats the way it is.

 

Here is the basic formula for heat transfer of a heat exchanger:
Q = k * A * delta T
Q - flow of heat in watts
k - constant, in this case how well the radiator works
A - area of radiator
delta T = logarithmic mean temp differece of outside air temp and coolant temp
An increase in delta T will increase the amount of heat transfer.
Consider outside air temp constant.
Calculus would have to be used to obtain a good measure for delta T, since the coolant temp decreases as it flows through the radiator. This decreasing of coolant temp flowing through the radiator causes a lower delta T, which will lower Q. Speed up the coolant flow to keep the coolant temp higher throughout the radiator, thereby maximizing delta T and increasing Q.
Removing thermostat - increases flow in radiator - increases Q

it's not true(no thermostat = hotter), unless there is a very strange circumstance of a system design...required backpress..etc
small holes in thermostats is used to pass gas
no thermostat - no temp regulation - not good

 

Thank You.

 

Now wait one minute.

Look at the thermostat. It opens DOWNWARD, some have little jiggle valves and some have small holes that allow AIR mostly and a very small (VERY SMALL) amount of water to pass through other then that there is virtually no flow through the system when the thermostat is cold/closed. It sure does restrict and regulate flow! The water pump is virtually non existent at this time, it’s just building a small amount of pressure behind the thermostat, holding that water in place. The water pumps job is to direct water through the system but IT CANNOT force a thermostat open. The flow of the cooling system is from lower hose into engine via the help of the water pump through thermostat to upper hose then radiator and the cycle begins again. If there is no restriction or regulation in the system and lets say your traveling at a constant rpm like highway driving the coolant will constantly circulate at the same speed. Now IF the coolant does not spend enough time either in the engine to transfer heat into the water or in the radiator to transfer heat out of the water the engine will run hot.

The first step transfer heat into the water. The coolant in an automotive system is designed to transfer heat into the water away from the engine. If there is no restriction or regulation this will not work the way it is designed to. An example would be steeping on a hot sidewalk in summer with no shoes. If you stay in the same spot the hot concrete will transfer heat into your feet away from the concrete like a cooling system is supposed to do with engine heat into water. If you run across the sidewalk there is very little heat transferred into you’re feet like water flowing through the system with no regulation.

The second step heat out of the water. Without the same regulation that transfers heat into water you cannot transfer heat out of water worth squat if it does not stop long enough in the radiator to do so properly. The cores to regulate some flow but they only regulate it as a small restriction if there is nothing stopping more water being forced through the system behind it the water is just going to flow back through the system again not cooled down more then a few *. Its like blowing on a hot cup of soup, if the amount of soup in the cup stays the same sure it will cool down enough to drink it but if someone is pouring more hot soup into the cup while your blowing it isn’t going to cool down. It’s going to remain the same temperature. This is what happens when you have no thermostat to stop or regulate the flow of water.

A properly working system the water/coolant will all start out the same temp not flowing through the system until the water has had enough heat transferred into it to reach the thermostat opening point. Then the thermostat opens, the hot water from the engine flows into the radiator, the cooler water that was in the radiator is sucked up into the engine dropping the engine temperature and closing the thermostat to allow the engine to transfer heat into that water and the water that was just released from the engine into the radiator to cool down.

Circle track engines use a plug/washer to regulate flow because they know what size plug will reduce flow enough to allow the coolant to cool. They use many different sizes depending on what RPM the engine is going to average. Drag racers use then also, many don’t use a thermostat or plug at all because their engines spend only a few seconds operating so heat transfer isn’t a big issue with a drag car that averages 5 minutes run time on a good night.

As far as the plugged radiator. If the engine was running hot and you removed the t-stat and it runs perfectly now. It means enough of the cores are plugged in the radiator to slow down the coolant flow enough to cool before going back into the engine.

Cooling is very simple once you understand how the system operates you don’t need X’s and O’s and long equations to explain how something works, common sense works best.

 

You forgot that the water recircs through the engine at all times via the bypass, no matter what the temp. When the water gets such a temp the thermostat allows water to pass the radiator where it mixes in the right hand tank with the hotter coolant, from the bypass discharge before entering the pump.

 

The bypass is soo small and flows such a tiny amount of water it's not even worth considering in the equation.

 

You don't understand that basic equation.
The bypass passage is larger than the coolant holes in the headgasket.
You can't argue with physics.
Think about it: Following your thought, hot water could travel through a tube so fast, the tube would not get hot or be able to heat air. Don't think of the temp of the coolant leaving the radiator needing to be cooled, but the heat from the coolant needs to transfering to air. If the water was to travel very slow through the radiator, the water temp would go down, but the air going through the radiator would be a lower temp, thus less heat transfer.
As long as the tube of the radiator is hot, it will transfer heat. The hotter the tube, the higher rate of heat transfer.
Think heat transfer.

Here is a heat transfer calculator:
http://www.monachos.gr/en/calculator...ing_piping.asp
change the flow rate and watch the heat transfer
More reading:
http://chemeng1.kat.lth.se/staff/ulf_b/mp_heat.htm
If you don't understand, please don't explain.

 

that is true in a non closed system. but the pipe is going to be heated a tiny bit. turn that pipe into a circle and have that hot water go by that spot again and again and the temp will rise.

 

My whole cooling system is brand spanking new. It STILL ran cooler w/out a thermostat than it did w/ a thermostat.

BTW, i drive my car 60 miles 5 days a week. Thats pretty far if you ask me.

 

This is my last try explaining this.

Imagine one water molecule traveling though the radiator. Sure this one molecule will lose more of its individual heat if it went slow vs fast, because it spent longer exposed to an area where it could release heat. Sum all of the heat lost by all these slower traveling individual molecules and compare to below.

Now, with the flow increased the individual heat lost of an individual molecule will be less, but since the flow was increased, more molecules will pass through the radiator for a given time. There will be a greater number of molecules releasing heat for a given time. Summing all the heat from lost from the greater number of individual molecules passing for a given time will be greater than the sum of heat released by the slower traveling molecules expained above. The reason more heat is released is because a greater difference in temperature of air vs radiator surface(coolant) is maintained.

I hope all this time I spent on this topic will help.

 

ok, so do u agree or disagree that no thermostat makes you run cooler? i can't see through all your technical talk..

 

Removing the thermostat will not make the engine run hotter. People should also keep in mind that the engine can run too cool.

 

82, in some situations it can cause the engine to run hot. Your system is all new and you drive 60 miles and your car runs fine. that means the rpm you drive at it sutible enough to cool efficently, just like the circle track engine that uses a plug type restriction to allow heat transfer.

BMent,
What Don is saying a lump sum of heat will be trasfered quicker if it flows through the radiator quickly instead of slowly.

I'm sorry Don but thats not true in an automotive cooling system. It works fine in a power plant cooling system where a large sum of water is being passed over a hot area but that water is consantly mixed with cooler new water. We can go over this a couple hundred times I dont mind.

 

Very interesting.

I did some data logging yesterday with the motor idling in neutral, no thermostat. the coolant would hit about 200* (fan on temp) then cool off really fast to about 185* then it would SLOWLY work its way down to 165*ish and wouldnt go any lower with the fan running. this with stock radiator, stock fan, high flow water pump.

when i put the 195* thermostat in, i didnt do any datalogging i just watched the water temp sensor (in the intake manifold) the water would hit 200*(fan on) then cycle down to 194*~ and Stop there, then suddenly it would drop to about 187*~ and slowly rise back up to 200*. I think that was the thermostat opening and since the fans were running and the water wasnt moving it cooled off alot in the time it was waiting.

Then I drilled 2 1/4" holes in the thermostat. the coolant would hit 200* a little slower than before, and would cool down and continue cooling even below the thermostat closing point.

so theres some hard data for you, engine idling, no load, steady 20* of spark advance and about 850 RPMS. probably running a tad lean, i cannot use the 02 sensor yet there is no exhaust.

 

SSC

You stated,"but that water is consantly mixed with cooler new water"
that is what happens in the right radiator cap in the gm style, if the bypass is still connected

http://www.monachos.gr/en/calculato...ting_piping.asp
This link shows a calculator for heat transfer of a heat exchanger.
Once you change a value hit ENTER, then it will calculate heat transfer rate. Play with it.

An automobile's cooling system follows the same rules as any cooling system. It's all physics.

 

http://www.monachos.gr/en/calculator...ing_piping.asp

 

I just found this site.

http://www.grapeaperacing.com/GrapeA...lingbasics.cfm

My whole point was that coolant flowing too fast will not cause overheating.

This site explains it nice and simple why it may overheat without a thermostat.

If you understand all this, here is your reason to buy that high flow waterpump and use a higher flow thermostat.

Now I want to buy a high flow waterpump.

 

I have a *160 therm. and a jet fan switch that cuts on the fan at *200. My car will get to *200 in traffic (normal) and stay around *160 when I am driving around (normal). I believe that the thermostat is really meant to maintain your lower operating temperature. If your engine water temp goes below your thermostat rating, the therm. will close which heats up your water. When the engine water temperature goes above the thermostat rating the thermostat will then open to try and maintain the optimum temp (therm. rating) you are wanting the engine to run at. Well, just opening up will not keep your engine water temp where it should be (especially in traffic in August) therefore you will need a fan(s) to keep your engine from getting too hot.

My $.02 worth in a nutshell= Thermostat maintains lower temp. and fan maintains upper temp.

 

Agreed, the thermostat is the lower temp and the fan is the higher temp. Having them close is a good thing.

I like this explanation:
A common misconception is that if coolant flows too quickly through the system, that it will not have time to cool properly. However the cooling system is a closed loop, so if you are keeping the coolant in the radiator longer to allow it to cool, you are also allowing it to stay in the engine longer, which increases coolant temperatures. Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures.

Years ago, cars used low pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would overcome the radiator cap's rating and force coolant out, resulting in an overheated engine. Many enthusiasts mistakenly believed that these situations were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool. Using restrictors or slowing water pump speed prevented the coolant from being forced out, and allowed the engine to run cooler. However, cars built in the past thirty years have used cross flow radiators that position the radiator cap on the low pressure (suction) side of the system. This type of system does not subject the radiator cap to pressure from the water pump, so it benefits from maximizing coolant flow, not restricting it.

 

EXACTLY. the key words there.. closed loop system..

 

The truth in a more abstract form might be this. Your ideal temp is 195. Your ideal situation is to keep your car at this ideal temp as much of the time as you can.

Ideal world we wouldn't need a stat or a fan. But things aren't ideal all the time. So GM puts a stat in there for a reason.

Reason: Divides your cooling system into 2 parts or capacities. Smaller and larger as smaller capacities warm up quicker larger capacities provide more cooling capabilities.

Closed = smaller capacity for quick fluid to op temp operations.
Open = To dissipate higher levels of heat.

The fan is put there as an emergency measure if it goes to app. 234.

More abstract you say?

Next winter take the thermostat out of your heating system in your house. Can you still get heat. Yep. Will you be comfortable. Nope. You set your home thermostat to a certain temp to ......

Try and maintain that temp.

It is no different for your car.

 

I've read through this entire thread and I'm here to tell you thatrunning a car WITHOUT a thermostat or at least stat with the guts removed (or a plain flat washer of the appropiate size) WILL let the water flow through the radiator too quick to cool it properly. I speak from personal experiance! I have raced oval tracks--both dirt and asphalt-- always a skinny block chevy--and was head wrench on a sprint car for 3 years. When I first started racing in the lower basically stock classes, we were constantly fighting overheating problems. We tried everything! different radiators, fans, waterpumps, additional electric fans--until I finally learned what was going on. After talking to other racers, we found out that everybody runs some kind of water restrictior so the water will not circulate through the rad too fast to cool it off! Now, I admit that the engines are running at constant high rpm's which is different from street driving, and we never ran any underdrive pulleys. I'm sure there are a few of U out there that are using old soft radiator hoses in need of replacemant that could benifit from running no stat because the hose is collapsing and slowing the water flow to do the same thing. But the bottom line is that I WOULD NEVER run a car without a stat--street/strip/oval/rally/ it doesn't matter. I've been burned by hot radiator too many times(no pun intended) and have learned from my own personal experiances--not just what some other guy told me that he heard somewhere once!

 

hey guys

i was out playing on the bypass the other night. I ran the car hard.but wehn i was about 95 ish in 3rd gear rpm's are up i noticed that the temp gauge was rising. So what i'm tring to get at if higher flowing water helps maintain cooling. why did my car start to raise the water temp. it got up to about 220 degrees . I know it can't be airflow @ around 95 mph. the only thing that i could guess is that the water was flowing to fast thru the radiator for a long period of time. the rpm's were about 5k. when i shifted the car to overdrive and cruised at around 100 the water temp came back down. do you think it was the rpm's coming down helped it to start cooling about down or that increase in about 5-6 mph? i think it was the rpm's coming back down that help it because the water flow slow down some to help cooling.

I think that if you slow water down to fast it will over heat. i also think if it flow too fast it can cause run away heat build up. so you need to find a happy medium between the two.

BTW my car has a new stock style radiator,180 therm. new belts and hoses. car never moves from 190-200 degrees with the air one sitting in traffic on a 90 degree day also

 

Now U got it! Kinda!

Don't forget that heat is a by-product of making horsepower. It's normal for the temp to rise in a situation like this. Cooling systems for street or strip are for the most part, are not nearly as efficent as roundy round or rally type cars. That's why they have all these big bad *** aluminum radiators for racing applications--many would be overkill for street/strip.

Of course there's always the possibility that the tempory temperature increase could be caused by one or both of your rad hoses collapsing in on itself, severely restricting the water flow to the point that hardly any water was passing through the rad to be cooled! Your hoses are in good shape--right?

You know, in another thread somewhere, somebody said he would NEVER run "one of those universal hoses". Well let me tell --AGAIN FROM PERSONAL EXPERIANCE---those ridges you see on the universal hoses actually make them stronger than a molded hose! They will not collapse as easy! Next time you go to the parts store, ask the counter man to grab a universal hose and a molded hose--any type/any application--doesn't matter as long as it's the same diameter/same thickness--then squeeze them like if they were collapsing in on themselves. Believe me, the universal hose will be stronger, but don't take my word for it. Go do it and prove it to yourself!!!

If you have a stat in your car, I doubt it was circulating too fast. It was probably the heat being generated by power ot the hoses collapsing in on themselves.

 

Any time you are "Under Load" your temp will rise.

Going uphill.
Towing a trailer.
A/C On.

And yes 100 mph in 3rd gear.

 

The water temperature guage tells you one thing- the temperature of the water. It does not tell you the temperature of the thing you are trying to cool THE MOTOR.....

If you remove the thermostat, the water will not spend enough time in the MOTOR picking up MOTOR HEAT.

Therefore the water temp guage can/will read cooler without a thermostat when in fact the MOTOR may be infact HOTTER.

Removing the thermostat is a bad idea.

The worst result is increased engine wear.