E.O.S. has been around for 50years that I know of. I sold it when I was a parts man back in the 50's and 60's. I haven't been in a Chevy dealership in decades so I don't know if they still carry it. Basicly it was just an oil thickener like STP.
And as Jeff mentioned this subject has been beat to death, not to worry unless your talking about a high performance engine.
Denny G
