Type of oil to use?

Going to have to do something about this oil leaking, but what ever we do I need to get the correct oil for this M135 six cylinder GMC gas engine.
I was told at a parade that modern oils do not have the additives needed because of something to do with the bearings for the cam? He said that if it is the wrong oil it would wipe the lobes right off the cam?
We also have a 53 Wills with the old flat head and I would assume the same is true for it.
Anybody know what we should be using???
Thanks

I don't want to get into another pissing contest or tell you what oil to use. Here is a article if you just want to read more about zinc levels or google it. The main thing would be if you start to use zinc additives is don't over do them. Blackstone labs is a must if you add additives I believe. Much easer to spend more money special made oil then to try and mix additives I believe.http://www.classiccarmotoroil.com/

I read that the Canadian Military switched to using 15w40 in these engines. I have also heard that Shell Rotella 15w40 has the zinc additives that old engines need. You'll have to decide what is best for you but this is what I plan to run in mine when I get her back on the road.

• Shell Rotella T which is a conventional (mineral-based) oil that was originally formulated for diesel engines. Rotella T still contains 1,200 parts per million ZDDP, according to Shell – which is as much as five times the amount found in other oils. Don’t sweat it that Rotella was/is “for diesels.” It’s also an excellent choice for older, non-emissions controlled engines with flat tappet cams that need their ZDDP. Rotella’s also modestly priced and readily available at most any auto parts store. Shell also markets a synthetic version of Rotella that offers even more protection – as well as longevity and a 5W-40 viscosity for those who operate their vehicles in colder climates. Standard Rotella comes in a heavier 15W-40 blend.

Thanks guys, I will look this all over well. We were not aware of this years back when we started running these vehicles. But a gentleman at a local parade mentioned it to me and I thought I better check in on this.
Thanks

Lots of people use 15W40 in the old gas engines. We use it in our M151’s. It seems to work very well for lots of people.

Flyingvan911 said:

Lots of people use 15W40 in the old gas engines. We use it in our M151’s. It seems to work very well for lots of people.

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Yea for a long time the hot rod guys would use it for high spring pressure engines and new cams. Now there is plenty of break in oil offered with much higher levels. Last time I sent my Rotella in to lab it was running about 1200 ppm. Reading articles 1200 to 1600 ppm is a ok running range.

Thanks all. One last question?
Does it not matter that the Rotella T is (I would suppose) a detergent oil??
Thanks

Another question PLEASE???
Stopped in today to buy the Shell Rotella T oil.
Found out there are several "T"'s?? T1, T4, T5, T6 and maybe even more.
I read everything on the jugs but it said nothing regarding ZINC, just what standards it meets, which really means nothing to me.
I thought you all might be meaning the T4, as it is the 15 W 40 eight, but want to be sure before I but it?
Can someone set me straight???
Thanks

over 50 years in my old ford jeep..all the while on shell 50 (straight oil). Still runs like a 'train'. Never been touched!..What can I say?
Pee,ess..All my vehicles of the M series are running on it.
Pee..pee ess!..I do however add Molyslip to every engine.
gearbox.
Transfer case
and Axle.

Brad, I think you want the T4.

We should also chat about different types of oil filters when we talk about different types of oils.

Non detergent engine oils and the Early Deuce oil filters are compatible from what I read in the manual. I run 30 wt non-detergent mostly because the stovebolt boys I hang with are old school, my trucks like it and I like it.

I'll keep hunting for the article that evades me right now but there's more discussion required on the limited capabilities of our filter design.

m1010plowboy said:

We should also chat about different types of oil filters when we talk about different types of oils....there's more discussion required on the limited capabilities of our filter design.

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Very good point. I had not thought about this.

Non Detergent vs Detergent Oil in Stovebolt GM Engine

m1010plowboy said:

We should also chat about different types of oil filters when we talk about different types of oils.
Non detergent engine oils and the Early Deuce oil filters are compatible from what I read in the manual. I run 30 wt non-detergent mostly because the stovebolt boys I hang with are old school, my trucks like it and I like it.
I'll keep hunting for the article that evades me right now but there's more discussion required on the limited capabilities of our filter design.

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You raise a good question of detergent vs non detergent oil. From my point of veiw it is a matter of what has the engine been running, if non detergent stick with it, changing may result in leaking. For stovebolt Chevrolet as in CMPS read this as leaking more.

Now running non detergent does not mean that sludge will build up in the engine, if you change the oils hot and regularly the engines can stay amazingly clean. My HUP engine ran from 1945 to 2011 with non-detergent oil and was never apart. When I rebuilt the engine I change over to 30 non-detergent.

Cheers Phil