TekViper

forgive my stupid question but what type of oil is best to use in my 3.1L v6? it has about 72k miles on it if the odometer is reading correctly, 1990 firebird. Regulare or synthetic? any brands better the the rest? and 5w30 is what im looking for right?

thanks

TomP

Well, you're on the right track with the mileage information; the more miles a motor has, the more likely the seals are worn out. Synthetic molecules are smaller than dinosaur oil molecules, and can slide past worn out seals, and cause leaks. Some guys try it on their high mileage motors, and get tons of oil leaks. Other guys (i think there's a few here) have had no problems.

TekViper

synthetics will work better though if my seals are holding up right? is there any oil thats a middle ground between synthetic and dino? maybe a thicker syn? i dont think the engine has ever been worked on, i have no maintence records from previous owners so im just assuming its never had work. guess i should just stick with dino to be on the safe side for a while and give synthetic a shot in the future? i just bought the car last month and still getting an idea on how its been maintained.

also TomP do you have a link to your famous tuneup guide? i dunno if you got it but i sent you a PM yesterday, i couldnt find the thread everyone was refering too.

Doward

I run 20w50 in like... everything I own

AGood2.8

Any new motor- I run 20w50 for 8,000 miles to set the rings (Rings are so hard nowadays it takes this many miles to break things in and seat. The I run Mobil One 15w50 full synthetic.

I have a V8 in a car that I bought new in '89 that I have put 400,000 miles on it and it is still ticking strong. I have never had the bottom end apart on it- original crank bearings! Engine runs smooth as silk but has lost aprox 20% of its power over the years (cam lobes are probably close to round by now )

TekViper

is it safe to mix half dino and half synthetic, same weight? im not sure what the engine is running now, i bought it last month. its past due for an oil change though. if i used dino and it has been using syn up until now would that hurt anything? on the other hand if i went with syn and it had dino the seals might start leaking right? someone told me when changing over to synthetic you should gradually do the change over.

CC_HotRod

Castrol 20w 50 for me also.

TekViper

how come no one runs 5w30 like the cap says to use?

TekViper

alright well i bought some mobil 1 10w30, guess i'll see how that goes. *crosses fingers*

firechicken_-54

you should try semi-sythetic i have it and i've had no leakes what so ever, my car has 2525000 kms

TekViper

too late, doing the oil change tomorrow. i'll let u guys know how it turns out

might change over to semi synthetic the next time around tho if its cheaper. i payed 30 bucks for 6qts of mobil 1 10w30.

TomP

I use 10w30... the "w" stands for winter, not "weight". So in the winter, when the car's cold, the oil's a bit thicker than 5w30... which treats my seals better. Before I knew my distributor seal was leaking, I thought it was my rear main. The thing would drip like crazy. My dad suggested I run 10w30, and it slowed the leak down a lot. Then I found out about the distributor o-ring from my mechanic; after he changed it (he was rebuilding my distributor to find out why my car wasn't starting, turned out it was a bad connection), I didn't have any more leaks.

You can buy a semi-synthetic; it'll be cheaper than full synthetic.

Joe_L

Thats a lot of km... J/k I am sure its a typo, should be 252500.

As far as oil, I ran 10w30 with a small container of that STP treatment. The engine was older, and probably was not well looked after before I bought it, so I figured if I put in 5w30 I would see some oil smoke when I was driving.

TekViper

yeah im putting in mobil 1 10w30 in tomorrow. how long should i let it run before my next oil change? i think it is running dino right now so id probably have to change it sooner the first oil change after right?

89cmrodriver

i just changed mine the other day and used moible 1, great stuff except i couldnt get the drn bottle open..lol i tried and tried then igot the vise grips...lol i learned that u never change oil on a windy day and that oil doesnt taste good...smells good but DOES NOT taste good

and that is all i have to say

PS: anyone will give me helpfulhints on my 89 RS to 89 IROC clone id be glad to hear them

Nixon1

Hey Tom...I leaked a quart a week from the distributor seal before it got fixed, and I ALWAYS ran 10w30 dinosaur oil! That's a hell of a bad seal!

Dale

iTrader: (12)

10w40 for summer, 10w30 for winter, reg oil for me.

If I use 10w40 during winter time, it ticks really bad when warm, let alone when cold.

TomP

Dale, why the 40 weight? I always thought 40 & 50 were too heavy for our motors... or am I way off track?

89V6FBIRD

Tom, I just changed my oil w/ 10w-40 Valvoline Maxlife. Trying to mask that tick I have. Summer I'll probably run 20w-50, but it is so-cal weather, and the coldest we'll see here is high 40s overnight to 60s in the daytime, brrrr it's cold!

Dale

iTrader: (12)

My s10 engine, dude before me ran 20w50.

I ran 10w40 in it, Now its just a garage decoration. Still runs.

The camaro I do too. It runs 10w40 with no problem. I put it in due to the heat down here.

MDv6man

I also use Dale's method of 10W-30 in the winter and 10W-40 in the summer. My friend who is a mechanic by trade said often going from 30 to 40 weight in higher mileage engines reduces the amount of blowby from the rings or valves.

Why do I switch with the seasons? Hard to say. My friend uses 10W-40 year round. I guess I just prefer something slightly thinner in the colder months.

FYI this change did help my wife's old Metro. I was using 5W-30 and had to add 1/2 - 1 quart every week. the car did not leak or spit any blue smoke. I went to 10W-40 and only had to add a little bit between oil changes.

89IRO

I heard somewhere that 10w-40 is bad because it uses so many polymers in it to compensate for the wide range in the thikness (10-40)????? I've just always used 10W-30 Castrol in my 5.7L. Opinions? -89IRO

JoshDT91

iTrader: (1)

TekViper: I run MaxLife 5w30 and I have no leaks. The only problem I have is oil magically disappears from the oil gremlins. I thought it was my distributor gasket and o-ring but that was not it. The valve covers do not leak and the oil pan does not leak. Now I have been told maybe it burns oil. Well where I live you have to have the car emissions tested every 2 years. The car passes the visible smoke test and passes the emissions test when they put the car on the treadmill. So this leads me to think my rear main seal leaks although I NEVER find any oil on the driveway or wherever I park. I did put a vaccum gauge on the car and it read a little low for what it should have been. According to the gauge it said the piston rings could be worn, well I guess with almost 160k miles they would be Anyways...

Once I am done with the case of MaxLife I have I am going to try Mobil 1 5w30. I have put it in my car a few times and never leaked it or seemed to lose any more than I have with MaxLife. As for running thick oil why do you guys do it? Sure it masks oil leaks and such but it also robs you of power. I was putting in 10w30 when I first bought my car cause that was what the previous owner was using. Then I thought what about using what the cap says and put in 5w30. When I put it in I swear the seat of the pants gauge told me I had more power.

89IRO

Anyone?

JoshDT91

iTrader: (1)

89IRO: I'd just use what is recommended unless your engine is leaking oil or has a large oil consumption problem.

89IRO

So even in the So Cal summer, I should stick to 10W-30? I shouldn't go to something a little thicker? -89IRO

JoshDT91

iTrader: (1)

You can stick with 10w-30 no problem. According to the American Petroleum Institute if the lowest temperature you expect is 32 degrees fahrenheit then 10w-30 is fine. Since the lowest temperature you could expect in Southern California is about in the 40s 10w-30 is fine. You may want to look at the API motor oil guide at http://api-ep.api.org/filelibrary/ACF2AD.pdf That might help you out, but I would also say go with what you feel performs best. At higher temperatures 5w-30 will be realtively thin compared to 10w-30 at the same high temperature. So it's up to you unless someone else has a better analysis of it.

89IRO

So the only time I would run like 20W-50 is if I am living in the middle of the desert where it easily gets to 115 right? The highest it will reach here in So Cal in the summer is no more usually than 100-103. So you all think 10W-30 is thick enough to protect my engine this summer? More opinions? -89IRO

JoshDT91

iTrader: (1)

This kind of reminds me of the seasonal change of the thermostat in the cooling system if you are into doing that each spring. I know in the simple camaro manual that GM makes I could swear it just says 5w-30 and 10w-30. When you get too thick you could decrease your gas mileage by making your engine work harder. One thing I have done with my car is have extensive data logging on simple things. I just use excel and log my gas mileage on each tank and right now I have about 3 years of data which is interesting to look at. That is one idea is put in the oil you want and check the fuel economy, with the gas prices the way they are out there I would be doing everything I could to get more miles to the gallon.

89IRO

You're right, I'm sure the 10W-30 will be fine for the summer. I am just a little more concerned with protecting my engine than I am with gas mileage. Oh well. I should be O.K. -89IRO

JoshDT91

iTrader: (1)

If you are really worried about your engine I have a suggestion for you. Amsoil makes oil testing kits for about $20. What you do is take the kit and when you change your oil put some of the changed oil into a container. Then the shipping is included with the price of your kit and you send the sample to their lab. They then can tell you the state of your engine and if you are having any problems. You can see more information at their website http://www.amsoil.com/products/g.html I had a class my sophmore year of college, it was an engine and powertrains class. The professor showed us an oil analysis sheet from Amsoil and it had just about anything you wanted to know. It showed all the metals that were present in the oil which was interesting. I am yet to try it but it seems like a good investment.

89IRO

I may have to try that. -89IRO

Nixon1

........I just have to say....that is cool as hell. Do they do that for transmission fluid too? I'm about ready to rev it to 5 grand in neutral and drop it into Overdrive so I'll have a real, completely legitimate reason to rebuild it now.