Just out of curiosity. What oil are you guys using? Thanks, Todd

What ever 20w50 I can afford with some STP thrown in to make up for the missing zinc. Tom

Tom are you running the clearances larger with the 20/50?

I run Shell Rotella 15w/40, it is diesel oil. Also pour in 1/2 jug of GM EOS.

Just did a bunch of cam breakin's on a dyno and used JOE GIBBs from the shop. Tom

Delo 400 10-40 with a can of STP oil treatment - the pan holds 8 quarts and warm driving 2000 rpm is just over 30 psi

Erik, GMCs used 50 weight new. The clearances are normal at least they were in '78 when i built it. Tom

Whatever 5W30 is on sale.

5w30
I have Mobil 1 in the 292 right now.

I would love to use Rotella or Delo because they have (or did have) more zinc, but only if they had 5w30 or even 10w30.
20w50 is good for race engines that are built a little loose and torn down after a race.
Most engine wear occurs during engine warm up. 20w50 and STP would starve an engine for oil during warm-up and really srain the distributor gears. Modern engines have fast warm-up and run 5w20 and even 0w20. Fast warm-up helps with emissions as well.
I can't imagine how hard 20w50 and STP would be on an engine.

2009-1978=31 years of that combo. How long have you been driving yours? They haven't even made Mobil 1 that long. The whole point of zinc is that it adheres to the metal and helps on cold starts. Brand new GMCs used 50w. The guy asked what I used. I told him. This truck has more real hard miles on it than any other vehicle I have ever owned and probably any you have either. It's a daily driver and sleeps outside all year. It fires up at -15 and hauls hay and fire wood up a bad steep road when it's 110. It did a 4,000 + road trip to Lone Star Roundup In Austin. Most of it 75-80 mph. By the way the zinc in your diesel oils is gone too. link

I agree with the zinc missing in diesel oils. That is why I use GM EOS.
Which one of the STP oil treatments do you use?

There is also a synthetic diesel oil with lighter viscousity. I use it in my F450 Diesel. Starts way better in the winter.

Speaking of winter it sleeted here tonight, just a light reminder of what is coming. Tom

I just use the regular oil treatment. I contacted STP when the zinc went from the Delo and Rotella. Their rep said one bottle has enough zinc to treat 4-5 quarts. There is a new additive out now that is called ZINC but on the back label it says there is no zinc in it. How does that work? The only sort of regular, off the shelf, oil that still has zinc is Valvoline Racing Oil. Tom

Tom, thanks, I had forgotten which engine you had (for some reason I thought it was a 292, duhhhh).

I'm getting there. I got a clean head back from the shop last week. It's a cluster build,sort of an ADHD thing. There's the 292 I'm using to mock up the injector/turbo set up, the 292 "good runner" that's going in first, the 292 that's getting over built, and that Megasquirt thing. I know there is a less labor intensive way to do this but I'm locked in. I also have my entertainment duties here. Tom

I use Catrol Syntec 20W50 full synthetic. It has zinc in it.

http://www.castrol.com/castrol/genericarticle.do?categoryId=82915470&contentId=7032644

I also add a bottle of ZDDPlus for added piece of mind.

http://www.zddplus.com/

This is good news! It seems that the 20w50 is the only grade that has zinc. I searched the website and 20w50 is the only one I found that mentions zinc. I'll check it out at work tomorrow. Thanks Zeke I didn't know about Catrol. Tom

I've also used 20w-50 in every engine in every car I've owned since about 1973 or 74ish, except for my 2006 Mustang which the factory says to use 5w-30 in, and never had any problems from using it. Brands used were Castrol, Valvoline, Chevron, and Wal-Mart's house brand. Engine clearances were all standard.

When I was in college a whole bunch of years ago, I went on a tour of the Mobil oil refinery in Carson, CA, and found out some really interesting things about oil. The most interesting fact was that in a given geographic location, all commercially sold oil come from the same refinery. For example, ALL the oil in the south coast/ Long Beach area of southern Califoria is Mobil oil, regardless of what the label on the can/bottle says. Mobil refines the oil and then sells it to Exxon, Shell, Castrol, etc.,etc., who then package it in their own containers for retail. The only difference between brands is in the additives, and even those are almost identical. The most important thing to look for on the oil bottle is the SD/CC rating and the viscosity (10w-30, 20w-50, etc.) The brand name is relatively unimportant. Wal-Mart buys their oil from the same place that Chevron does. Pretty much the same thing with gasoline. Wherever there's a refinery, that's the brand of gas and oil that you're buying, no matter what it says on the pump or can.

By the way, RichardJ, most engine wear occurs during start-up, not warm up. Once the engine has oil pressure, wear isn't much of a problem even with a cold engine, and 20w-50 does a much better job of protecting engine parts on start-up than the lighter viscosity oils. Yes, the lighter oils do build up pressure marginally quicker than the heavier ones, but the heavy oils protect from scuffing better on start-up. Six of one and a half dozen of the other kind of situation, so take your pick. The most important thing regarding oil is to change it when it gets dirty and use a good quality filter. Other than that, I think it's mostly a matter of personal preference. OK, that's my two cent's worth.

I believe a few of the major companies are now packaging "muscle car" oil. It is aimed at the 60's and 70's era cars. I read they contain zinc additive package to protect older engines.

I personally use Mobil 1 in my racing engine, 2 Hondas, and 6.0 Ford Diesel. My son uses Delo 15-40 for diesel in his dirt car 357 Chev V8. Runs beteen 5000 & 7200 RPM with a flat tappet cam and we have no failures so far.

I run 15-40 rotella t with a quart of Lucas in everything. But it doesn't get below zero here in the the rain belt, either. Also, none of my engines are that fresh.