My first post here.. I have purchased a 1981 GMC 1/2 ton that has a 3rd gen 292 inliner.I have been searching for information on what weight of oil is recommended. I live in Canada so winter is a factor as well.. Does anybody have knowledge on recommended oil weights for this motor ?? Thanks guys ..

I'd recommend 10-30

Ron

Around here, Midwest. I run 15w40 rotella. It does start in the winter, but not driven. In winter as Ron says 10/30. Rotella also makes a lighter weight synthetic, I run it in my diesel for winter, it starts great. Tom

Thanks for the info guys..

If you have non roller lifters your best bet its to find oil recommended for diesel use as it has more additives which are more "friendly" to your lifter/cam combination. There are some "hot rod" oils now being advertised for older engines which may also serve you well.

From personal experience stay away from heavier weight oils unless you use your vehicle for long runs. Short trips will make a mess of your engine with higher weights. Good luck

I rebuilt my 292 about five years ago. The breakin oil and first couple of changes was with regular 5w30 oil. Since then it has 5w30 sythetic.

There is never a good reason for using heavier oil than is needed, especially in a cold climate like Canada.
Yesterday the temperatures in Southern Calif was over 110 deg in my area. I took the '67 out at mid-day for a couple of errands making four stops.
The AC was blowing cold, the engine temp gauge was in the cold and the oil pressure gauge was above the half where it always is. The '67 GMC gauges has no numbers, just C & H and L & H.

I would love to use an oil with more zinc, but there is no way I'm going to use w40 oil to get it.

The anti-wear oil additive is zinc dialkyl-dithio-phosphate, referred to as ZDDP. The dialkyl-dithio-phosphate is the active part. The latest 'CJ' rated diesel oils also have reduced ZDDP. You can Google "ZDDP" and find numerous articles with plenty of information.

There are several additives available with ZDDP.

The one I use is STP in the blue bottle (1/2 bottle per change) with moble one synthetic.

That's in a Bent 8 though (it's my designated beater / plow truck).

So roughly 7 Quarts 10W30 Mobile 1, and 1/2 bottle STP.

Last I checked their website, STP still had the ZDDP, but I only use that vehicle to plow my own driveway and haul trash anymore so it doesn't get alot of miles.

I rebuilt the engine a few years ago due to the cam going flat and a certain brand of orange colored oil filter letting the metal from that score the mains and rods.

That was before I started adding the STP, or using syntheic in that engine.

I definately not an expert on oils but I ask a lot of questions of the people who I feel have the knowledge. The tech rep from Joe Gibbs Racing Oils said that the zddp additive can be removed by a good oil filter. Oils which had the zddp pre-blended were not suseptible to this. He stated that Joe Gibbs Racing was loosing camshafts when Joe took over the cars and that's why they went into the oil business. They too make some "Hot Rod" oils and for guys who don't use them as daily transportation the cost may not mean as much. They like their racing oil very much ($$$) as reflected in their costs if you check.

A friend of mine who rums in Super Stock Eliminator in the NHRA was ony getting 12 to 15 runs out of Mobil 1 before loosing power. He could get 20 runs out of the Gibbs oil.

Gibbs does everything by engine clearances for recommending weights...I swear I put water in my race engine but maintained 80 PSI..............Good Luck

Very interesting, suggests that the additives are a suspension either using much larger particles, or they clump together.

Check out http://www.bobistheoilguy.com/forums/ubbthreads.php for a plethora of information.

A know at least a few racers out here like Brad Penn Racing oil. http://www.bradpennracing.com/ Green stuff; Pennsylvania crude.

valvaline vr-1 racing oil has zddp in it & is available in the parts store. it doesn't cost any more than "street" oil. i use 20w50 or 30 weight but i'm sure there's light weight available.

Here's another place to get ZDDP oil additive http://lesfrickshun.com/

Several 'local' old time machine shops recommend this product for all flat tappet cams. It's about $8.00 a quart and one qt is needed per oil change to sub for one of the normal grade. Pretty reasonably priced as compared to most of the 'racing' oils.

I've been using it for a year so I don't have any real proof of how it well it works - yet. I figured it to be relatively cheap insurance for the cam.

I looked into the Joe Gibbs oil, which everyone I've spoke to claims it is great product, but figured that for the price I could buy a new cam just about every 5 oil changes. I thought for that price I should be paying for a guarantee, not insurance.