I originally posted this information to a message on this forum about "Isky Cams", however it seems to apply here as well...

The Diesel Oils are great, but unless they are API CI-4 rated, they don't have the necessary "minerals" in them to work properly with Flat Tappets. Most of the current formulations of Diesel Oil are API CJ-4 rated and have had the desireable Zinc-dialkyl-dithiophosphate (ZDDP) engineered out of them. Look at the bottle markings before you buy.

You can also use Regular Gasoline Engine Oil - if it is API "SF" rated. This vintage oil contains the proper amounts of ZDDP but is now usually available only at stores specializing in Racing Oils such as Valvoline VR1 or Kendall GT-1

Strange as it seems, Wal*Mart also sells a SF rated oil - Brand name "Accel" - which is specifically marked as SF Rated and for Engines manufactured before 1988! The SF rated oils were engineered out of the market as they shorten the life span of the Catalytic Converter. Not a big concern to the owner of a 1960 something Volvo.

Finally, try and find some GM "EOS" or a generic equivalent. This is a special additive for use in the initial Break-In operation of new Cams. Current Oils (Rated SM) seem to be death on the Cam and Valve Train of Flat Tappet, solid lifter, engines.

If you really want to get educated, try this link: http://www.ttalk.info/Zddp.htm

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