EOS Question...Duke?

[Donald M.]

Duke, I would like to add a pint of GM EOS to my oil to replace the ZDDP that is missing in the "SM" rated oil I currently have in the engine. Now the question: GM, on the reverse side of the EOS bottle states that EOS is not to be used as an engine oil supplement, but only as an "assembly lube". Can I add this one bottle to bring up the ZDDP until the next oil change(using CI-4 oil)without harm to the engine?
Thanks!
Don

[Joe L.]

Re: EOS Question...Duke?

Don------

Absolutely YES. GM should state that EOS "is not to be used ROUTINELY as an engine oil supplement". In a situation like you suggest, I would say that it's 100% ok to add a pint of it.

[Alan Drake]

Re: EOS vs CI-4

Since Don is using CI-4 oil isn't the adding of EOS un-needed? Or is more better?

[Joe L.]

Re: EOS vs CI-4

Alan------

Don is, apparently, using a gasoline service "SM"-rated oil. That's the reason for his concern from what I understand----these oils may have a very low concentration of the zinc EP additive. Adding the EOS will provide what might not be there.

[Duke W.]

Re: EOS Question...Duke?

I guess the EOS instructions have changed, but way back when the recommendation was to add it to the oil for breakin, but not use it after that.

Notwithstanding the above, running SM oil in your engine until the next oil change will not do any serious harm, and you are wise to switch to CI-4 oil.

Duke

[Clem Z.]

Re: EOS Question...Duke?

i was told not to use EOS after cam breakin because it caused ash and this burned pistons in race engines. back in the 60s i was told to use aviation oil in race car engines because it was ashless. i know gulf did this with their racing corvettes

[Donald M.]

Thanks Joe, Duke....

I think the EOS willl be Ok, especially with a stock 300 HP driven conservatively. I'll switch to CI-4 next oil change.
Don