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1955 Chevy

Dear Tom and RAY;

I have a 1955 Chevy pickup and want to know if the oil companies removed the ZDDP(Zinc-Dialkyl-Dithio-Phosphate) from the current oils. I have a 350 Chevy engine and need to know if I have to add a additive. There is additives on the market and need to know if I need them due to my non-roller rocker engine.

We had this post before. Rest assured there are enough anti-friction additives in modern oils for your 350 engine! ZDDP is not eh only additve that is an Extreme Pressure (EP) additive.

Well that’s what I used to think Doc, but it would appear that the amounts of them keep falling in the new oils. It’s really only an issue if you’re running a flat tappet camshaft, which this 350 may or may not have. The quick solution that some of the cam companies and engine builders are recommending is to run Diesel oil which is allowed higher levels of this stuff. However, this is starting to change too.

Thot55-if you don’t mind paying top dollar start buying Redline Synthetic oil-based on the lab results I’ve seen it’s got anti-wear additives up the wahzoo. If you’re cheap though, you’re only choice may be old-style diesel formulations.

Both Shell and EXXON have “mixed fleet” oils that are good for gas and diesels. The old 350 does not need the latest formulation,such as SM, so it would be a good choice for having peace of mind.

I’d recommend Mobil-1 synthetic or Shell Rotella oil if you want to use a conventional oil. Either of these are likely far better oils than what was available when your motor was made.

Am I the only one who picked up on the fact that a Chevy 350 motor didn’t even exist in 1955? As I recall it didn’t debut until the late 1960’s, so this 350 could be old or newer, carb’d or injected. Roller cam’d or flat tappet…

I think the ZDDP issue is way overblown. Even the cam makers such as Comp, Crane, etc. state that a new cam should be properly broken in with the enclosed assembly lube followed by running your normal motor oil. Of course, they’re been recommending that for years.

It seems like many of the flat cam lobe complaints come from the performance boys. Kind of hard to believe a shaky rebuild, improper break-in, or thrashing on the race track would ruin a cam…

JMO anyway.

Actually, Dave, that was the first thing that came to my mind. I think the 350 came out in the late 60s. But with the design changes it underwent over the years, the OP could give us a little more info. This could be an LT1 for all we know.

Most 55 Chevies by now do not have their original engines. That was a 265 cubic inch, later on enlarged to 283, etc. I assumed the OPs car had had an engine transplant by now.