More Letters to Know

Okay, students, last class we covered IAT and OAT types of antifreeze.  Remember?  Now we will learn about another batch of letters.  Meet ZDDP.  Anybody care to tell the class about ZDDP?  Nobody?  Okay, students, ZDDP stands for Zinc Dialkyl Dithio Phosphate.  That used to be in your motor oil.  It was there to act as a lubricant for the old flat valve tappets (aka lifters) that rode against the camshaft.

Modern cars now have roller style tappets for better gas mileage so ZDDP isn’t necessary ….for those cars.  The cars that now qualify as antiques, later eighties and earlier, fall into the group that has flat tappets.  I see hands going up.   I know you all want to know what happens to old cars that don’t have the benefit of ZDDP.  The cam and lifters could fail prematurely as a result.  Now you want to know what oils still contain ZDDP.  There are a few and their numbers are shrinking.  There are also supplements that can be added to your favorite oil to insure your engine has some ZDDP circulating around your cam and lifters.

Oil Brands Containing ZDDP

Additives with ZDDP

Brad Penn
Royal Purple
Kendall GT 20W50
Swepco 15W40 306
Shell Rotella
Comp Cams
Champion Lubricants

Lucas Oil Additive

GM’s Engine Oil Supplement (EOS)
STP 4 Cylinder Treatment (Red container)
Risilone Engine Oil Supplement

If you would like to learn more, here are some interesting articles on the subject:

From the MG folks
Wikipedia technical article
Porsche Registry article
Macy’s Garage, Ltd
Corvette forum