Lately I've been hearing a lot of what appears to be B.S., but you guys here on thirdgen usually give me some pretty good information so here we go:

Is it true that full synthetic oil is harmful to run in my 86' 305tpi? I keep hearing that my motor was not made for synthetic, it will leak oil (even though I just replaced all the gaskets in my top half and serviced my heads), etc.

I currently run valvoline max life synthetic blend... Input please, thanks in advance.

 

Thats a hold over fear from the 1970's when synthetics weren't common place. You should have no problems.

 

It is all B.S. No worries. You'll be fine.

 

Awesome. I have been wanting to try that royal purple, they claim it increases horse by 3% and everyone is nuts about it. What do you guys run for weight and brand? Is 10w30/40 better than 5w30/40 for our 305s and 350s?

 

you may like the 5w30 for where you live as its not all that hot there is it? do you drive the car in the late fall or winter at all when its cold?

cooler temps will need less thick oil and the 5w30 ratings means it flows like a 5 weight oil in winter temps. 10 is a bit thicker in cold temps.

if its hot in the summer and thats all you drive, you may like the 40 weights since heat will thin the oil and its best to start with a thicker oil in that case

 

AMSOIL 10W-30 synthetic in the Camaro (and other roller lifter engines in the family fleet).

AMSOIL 5W-30 synthetic heavy duty diesel/gas in the '57 and other flat tappet engines in the fleet.

It's hard to believe there are still these old wives' tales out there. I shouldn't be running radial tires on the '57, either, according to that logic.

Of course, the RP stuff you've been hearing is primarily RP PR. They're about 4th on the quality list (AMSOIL, Mobil 1, Redline, would be my own personal ranking).

 

I've run RP, Castrol Synthetic and mobil1 in my HD Sportster. It didn't like the Castrol or the Mobil1, it loves Royal Purple though. I'm judging based on the engine temp (air/oil cooled motor) and noise. RP was the one that lowered my oil temps the most and also had the least amount of internal engine noise. It was the only synthetic I've used so far that was as quiet as the HD dino oil. HD motors are noisy, that's why we riders like to use loud pipes. It's so we don't worry ourselves to death when strange sounds come out.

 

The only problems I've ever heard of running synthetic is in an older motor. Like, the older crude oil may have formed sludge, sealing some potential leaks.

Running synthetic could knock those "sludge seals" loose & start the engie to leaking, because of that.

Any thoughts on that? Truth? Lie? Just theory?

 

yeah on higher milage vehicles it will clean out "sludge seals" sometimes, cause synthetics have better cleaners in them, but its worth the risk, my engines professor recomended not changing to synthetic on a car with over about 75k miles thats always been on conventional, because of this but i did on my 99 camaro at 85k miles and still no leaks 10k miles later....like i said its worth the risk....

 

True, but it's a matter of degree. The typical recommendation is to only use synthetic in mechanically sound engines - no sense in continually adding high priced oil to the crankcase so it can be pumped out the exhaust.

Synthetic typically will not leave the deposits petroleum oils do (and petroleum oils are better about that than they used to be), and tend to be better detergents than petroleum oils. So, the deposits left by years of petroleum oil use will be loosened by and contaminate the synthetic.

I've seen one engine since starting to use synthetic in 1983 that had so much sludge/varnish built up that it clogged the oil pump pick-up when synthetic was put in it. Even then, it took over a year before it finally failed. That was a severely neglected previously "trailer trash" owned car.

If the engine has had regular oil changes, it probably isn't going to have enough build-up to cause leak or clog problems.

 

yeah once again everyone listen to five7. he explained a little better thanks....

 

if clogging is a serious concern, and in some cases it should be. You can always "flush" the motor with a chemical add in or trans fluid.

99.99% of the time there is no issue. I used synthetic blend in my 87 up to 175,000 miles, i currently run full syn and have 315k on a 5.7 litre... never any internal engine work.

 

But at what mileage did you SWITCH? I'm pushing 170,000, and haven't switched, because I don't want a leak.

If it leaked, I could switch back, but still have the leaks, since there was no longer "sludge seals".

My engine runs GREAT though. It seems well maintained. Hell, I just pulled #1 plug to look. Only a SLIGHT yellowing on the insulator & I've had it 2 years & typically starts on the first revolution of the engine.

 

The back of most flush additive bottles say to remove the the oil pan and check the pickup screen. PITA.

What I would do-pull a valve cover on a car with some miles and look to see how much buildup there is. If there's a lot, I wouldnt run synthetic.

When I pulled apart my 90,000 mile 305 it had a quarter inch of muck stuck to everything.

Who knows what the person that owned the car before you put in the engine, or how long it was there.

 

Why? No matter how many times I've told my dad that synthetic oil isnt opaque black...... he always is against using it because he wont be able to tell when its dirty. Some things just dont go away.

 

What he doesn't know is he can't tell when petroleum oil is dirty. . .

I switched the original 305 in my Camaro over at 123k. Soon after I changed the valve stem seals (and valve cover gaskets). A little while later I changed the intake manifold gaskets (was leaking coolant from the ends - not synthetic oil related). I never had problems with leakage.

I've changed several engines over with 100K+ miles. I always use a crankcase flush first, and typically change the first fill of synthetic earlier than the normal recommendation.

Many people recommend using ATF as a running flush. I've never tried it, I don't have any reason to doubt those who say it works.

 

I've read about ATF being a good way of flushing all kinds of sludge and build up from an engine but will that cause the engine to start leaking motor oil after you remove the ATF,just like the synthetic oil could?

 

id just use a good blend imo

 

So much confusion lol... So it's probably fair to say that I, since I do not want to drop the oil pan and am on my stock oil pump, should not switch to full synthetic?

 

Let's start where you started:
As already stated, it is not harmful, it doesn't matter that your engine wasn't made for synthetic (it wasn't made for SJ oil, either), new gaskets is always a good thing but synthetic wouldn't make it leak, anyway.

Now there's a good waste of money. What that "max life" stuff has is additional plasticizers to soften up seals hardened by use of petroleum based oil. There's only so much room for stuff in any quart of oil, so in order to put the plasticizers in, they have to take something else out. Any idea what they take out? Me neither. But, it's probably something related to reducing wear. Plus, the Group 4 synthetics (AMSOIL, some Mobil 1, Redline, and I believe RP) have the same effect on seals. So, if you start off using synthetic, you'll never have to go to a high mileage oil later on. Besides, no plasticizer can fix cracked or worn seals, which is the next step after the seals harden.

Since the valve stem seals are the #1 SBC seal problem, and your heads have just been freshened up, as long as there wasn't bushels of crud built up in the lower engine, you shouldn't have any problem switching over to a quality synthetic now.

Then there's the issue of your username - did you start this thread as flamebait?

 

 

I've never had issues switching over to synthetic on any car... but then again I've never actually owned a Pennzoil car (the older truly paraffin based stuff). My dad had one, oh boy was there some buildup in that motor. All you had to do was remove the oil cap to see it. If your car was like that, I wouldnt. I'd say most cars dont fall into that category. My only issue with synthetic is cost, most people dont keep their cars long enough to offset the extra cost involved. By the time the engine is worn out, they no longer own it. It does work though.

 

The cost is actually in your favor. They say 10,000 miles or one year between changes. Even if you do it more often than that, you are probably saving money. It also makes more power, and gives better mileage.

 

I don't see the cost savings. Regular oil is good for at least 5000 miles at generally half the price.
I can see running synthetic oil in new engines but don't see why you would want to run it in a motor thats been running for 20 years on regular oil. What do you really expect to gain?

 

Horsepower, gas mileage, and engine life.

 

Horsepower and mileage gains are very minimal and possibly not noticeable. You might see it if you did the whole car.

I run royal purple 10W30 in my rebuilt 355.

 

Five7 i have a question for you, since were on the topic.

First off though, i just wanted to say, all oils are legally supposed to be "compatible" with one another. So its just a wives tale when someone says you cant run this in ur motor.

As for my question. What do you make of the oil change period??? A freind of mine just became an Amsoil dealer, and has been pitching me the oil for a while now. I gotta say hes pretty convincing.

But he mentioned, Amsoil says to change their oil every 25000 miles!!!! Mobil1 also is selling a bottle now that says 12000 miles! My lumina van takes mobil1 (has always used it), and for the past 3 years, it seems to only have been changed once a year......(this is daily driven roughly 25 miles a day). Seemed to be ok when i changed it, not thin or anything.

I used to work at one of those quick lube places a while ago, and i always got into arguments about service period. They always told me, oil should be changed 5000km no matter what. But why????

Synthetic will clearly last longer, it is a superior oil. I think the companies are just now advertising the fact. I would imagine its the same oil with a new packaging. What do you think?

 

AMSOIL has been saying 25k/1 year since 1973, and backs it up with warranty. Mobil 1 also said 25k/1 year when they first came out, but backed away from that in the 90's. As far as I know, Mobil didn't offer to pay denied warranty claims.

Why do quick lubes and oil companies stick with 3000 mile (5000 km)? Simple - to sell more oil.

I've been doing 25k/1 year, whichever comes first, with AMSOIL since 1983. They used to say change the filter at half that interval, but now have a filter that will go the entire change. That alone is a cost savings over petroleum oil, but improved economy and reduced wear will add to that even more.

The only "legal" part of compatibility is if an OEM requires you to use a particular product not commonly available in order to maintain warranty, they have to provide that product at no cost. Obviously, they don't want to do that, so SAE and API along with the OEMs have come up with rating systems for that purpose. As long as the oil you use meets the stated SAE and API ratings, and you use them in accordance with the OEM's recommendation (such as change interval), the OEM is obligated to honor the warranty. However, that does not mean that different brands have to be compatible with each other if mixed. But, since nobody wants to be a "black sheep", they make their products compatible. Of course, AMSOIL (and I'm sure others) say if you mix other products with their product, then you have basically reduced the properties to the lesser product, and all (oil manufacturer obligation) warranty bets are off.

 

What do you have to say about Amsoil in my 350? It has less than 5000 miles since rebuild. But sees high heat, and alot of revs every couple of weeks. I guess it would perform the same as my mobil1 that im using now.

But would it still be safe to change it at 1 year you think?

 

Depends upon how severe the usage is. You may need to change more often. AMSOIL would recommend oil analysis to determine change interval under non-standard conditions (such as a street/strip car).

 

Eh, power and mileage gains arent worth considering. You really need to be doing an oil analysis to determine a proper interval anyway, in my experience with that I'm not getting that many more miles to offset the cost. I've been paying about $1/qt buying dino on sale with rebates or whatever and I cant touch a full syn for less than $4 so its not worth it to me.

 

They've been stating less oil changes for a while, people just don't listen, or don't pay attention. You save money for that alone.

I've never dyno'd a car before and after, but everything I see in mags are 7+ hp, I know, I know. Thats all I have though.

As far as mileage, I know a few people in realworld, that have experienced better mileage after switching. Wouldn't it make sense, that if it creates less friction, that the engine will make more power, and also be more efficient, hence better fuel mileage. In a 11mpg car though, it would be hard to notice without a calculator. Also with decreased friction, you get lower engine heat.

And, I'm not sure if I'll say this right but, since its a better oil, you can run a lower weight, which in also increases power and mileage.

 

Yes you can save some money by changing it less, but I cant realize any savings with what the costs are. I havent noticed anything significant as far as fuel mileage is concerned. I can vouch for the wear properties but I think thats pretty well documented. I took apart an engine that was always run on synthetic at about 90k miles and the crosshatching was visible all the way up the cylinder with NO RIDGE or wear of any sort. But, the engine died anyway at 120k due to a lifter valley crack so the extra cost involved in the oil (I'm still saying there is, I do use it on one car per their instructions) was not worth the 'increased' lifespan of the motor. Such is life.

 

i switched over from blend to full syn after 100k, it was so long ago im not exactly sure when. I would never be afraid to run synthetic oils of today regardless of mileage. Right now the autozone has 5 qts of full syn pennzoil and a fram tuff guard filter for 19.99 no rebate. great time to switch

as far as oil change intervals you can never change oil to early, all it takes is one rpm to many to do damage, as with anything there is no way to tell what will happen next. i know people who lease cars and change the oil once a year or just before turn in and have "no" issues or as madmax states anything at anytime can happen.

 

IMO pennzoil really isnt that good look at the back of the bottle i bet they dont met nearly as many standards as these.,the best synthetics im my opinion In no particular order, Mobil 1, Castrol, Valvoline, and Amsoil....

 

20 bucks is darn cheap, but I'll never touch pennzoil. ******.

 

pennzoil meets and exceeds all of the standards, they wer victims of the same dinosaur mentality from the 70's.

hey batass what did they do to you ?

fyi - they have been owned by shell oil for the last 5 years

 

They made a mess on my garage floor. Waxy oil muck everywhere. I wont ever use them. I dont care how cheap it is. They obviously dont care about my engine.

Why are you so interested? What, do you work for em?

 

Are you running a roller or flat tapet cam? Acording to Comp Cams some of the new synthetics don't have the required additive for flat tapet cams anymore.

 

Flat tappet cams require an additional additive?

 

The anti pennzoil crowd is living in the past. Years ago all brands of oils made a mess of an engines internals.

 

flat tappet cams require zinc as an anti wear additive most of the new engines are getting away from those kind of components so oil companys are taking out the zinc to "help reduce" emissions... however most oils made for diesel engines still contain high amounts of zinc and is why they are recommended for flat tappet cam break ins

 

I was talking to an amsoil rep last year, and he said that they still have the zinc in their oil.

 

i dont work for any automotive companies, i just hate to see recycled bad information. Im quite sure that the watch dog and whistle blowers would have ran pennzoil/quaker state and shell oil out of buisness by now if there was some "flaw" included in the oil.

 

Not a flaw, just wasnt good oil. Theres too many great oil manufacturers out there to use pennzoil.

 

I swear, every time I see a thread asking about oil, particularly synthetic, I'm tempted to answer and lock it, just to prevent silly discussions like this long after the OP got their answer.

Horsepower, gas mileage, and engine life can all be expected to be improved when using a quality synthetic vs. a "meets spec" petroleum-based oil. Period.

Penzoil earned their bad rap back in the API SF days (early 80's) - they "met spec", and that's it. The stuff broke down and varnished/sludged up engines something fierce. They didn't get "run out of business" because they met the spec, but they've had to clean up their act (like everyone else) as API started including anti-sludge properties in the later ratings; in large part because of the sleazy way they went about business back then.

ILSAC GF-4 oils, including AMSOIL oils with that rating, have very little to no zinc in them (limited by the spec requirements) for emissions equipment reasons - reasons which don't include 3rd gens. Not an issue with roller lifter engines; if you have flat tappets, consider a diesel oil that is also gasoline (SL, for instance) rated.

I could go on about why you're wrong, max, but that's enough for now.

 

For what it's worth I've ran Amsoil 5/30 in my 2001 5.3 Vortec since brand new. I have 450000km on it now and it runs perfect and has all it's compression. I've usually go 7500-9000km between changes. I just don't have the guts to try 25000km between changes that seems a bit much.
I also have run the same oil in my 91'305 LB9 since I got it at 20000km. I have 165000km on it now and it still runs perfect. I realize that both motors were new when I started running syn so there was no sludge buildup or leakage issues.

 

The recommended oil for my audi is synthetic I believe. People that own these cars dont seem to like working on them themself.

So, I have good reason to believe that synthetic was put in everytime, and at 140,000 miles, there is very little buildup in the valvetrain that I can see through the fill cap.

I can't remember what the amsoil rep said was good about zinc, but I do know he said their oil has more in it than most. Whats good about it?

 

I had a 94 Ford Ranger with a 4.0L and it was perfectly clean inside at 150K. Synthetic oil was never used in it. I dont believe you need to use synthetic in every application to achieve a clean high mileage engine.

Zinc was an anti wear additive.

 

I run Mobil 1 5W/30 in my all my cars, and I've used Mobil 1 10W30 in all my motorcycles. Motorcycles are particularly hard on oil since the transmission and crankcase shares the oil. All that shear from the transmission gears breaks down the oil much quicker.

Every bike I've ever owned has run cooler and shifted better after switching it to Mobil 1. My wife's Ninja routinely sees 15K rpm and Mobil 1 has handled it without any problems.

Also, I've heard many people say that you shouldn't use synthetic to break in an engine. I think this is total b.s. Corvettes and Porsches come from the assembly line with Mobil 1. If the engineers that designed those motors trust it for break in, so do I.