What weight oil do you use?

[Wasted Income]

My motor's a '94 in my'69 and it says to use 5-30 right on the oil filler cap. That's what I've used till the last oil change. I put 10-40 in it since it is only driven in the summer (on nice days) and when I do drive it she's being beaten like one of those proverbial redheaded step children.

[Scooter]

Castrol 10W40

[colohusker]

I had a similar problem bringing the yellow beast home. Went to pick her up, and not thinking all I brought along with me was 5w-30. Changed it, drove around town for about 30 minutes, pressure was fine, coolant temp was fine, all signals go to hit the road for 300 miles. About 30 miles out, everything was still okay at 75, but had to slow up for a town and the oil pressure just bottomed out to about 5-6 at idle. Hit the gas station and bought some 10w-40 and changed the oil again. Next town the pressure only dropped to about 10 on the gauge. Think I'll run 20w-50 next and see what happens. Just my humble .02.....

Scott

[bowtie]

20w50

[XXL]

Nobody's 'fessed up yet... where are all you who use 90 wt gear oil and/or STP oil treatment?

Kenneth

[Project1970]

Originally posted by Mike C
I ran 10 40 for years and years, but a recent discussion on oils with a petroleum engineer has changed my ways! He said that 10 40 was the first variable viscosity oil and that either 10 30 or 20 50 weights take less additives and manipulations to achieve than the 10 40 and as a result, they were better lubricants. Take it as you will, but I have switched to 10 30 in my cars and 20 50 in my trucks.

I've heard similar things as well; some going so far to say that GM actually won't warranty engines that have been run on 10w40 because of that. *shrug*

Oh, and Stepside...are you talking about the original '70s LT-1 or the mid-'90s fuel-injected LT1? If the latter, watch that oil pressue...I've heard from a lot of F-Body owners and I have yet to see one that would build enough pressure on 10w30 synthetic, our '94 Z28 included. I think GM even addressed it once and their answer was the same as everyone else's - run 15w50 Mobil 1 instead of 10w30.

[68 Stepside]

XXL, I know a certain member with a 69 swb fleet that uses the 90w trick.....(bad bearings). He's driven down here 3 times (I think) in it, now, and no problems to speak of, besides the proverbial lack of OP. I had an 85 monte carlo with a 4.3, and that sucker used as much oil as you could feed her, until I put a quart of 85w140 in her, along with 20w50, The OP got better, and it didn't seem to use quite as much after that, and she ran a lot quieter too

As for the trucks, I'm going to be running 20w50 in the 406 (Stepside), and right now, the panel has about 1w10 in it, lol....the oil is old and gassy, you should see it....But my preference is 20w50.

TJ

(Sorry, I get a little windy when I've been up for almost 24 hours)