Reader asks about oil additive for older engines

Wheels: Paul M writers by e-mail:

“A while back you mentioned a fuel additive for older cars. You said that today’s fuels removed something that used to be in the gasoline of the 60s and 70s. Those of us with collector cars would probably be wise to add this substance to our tanks per your advice. I have a 1967 GTO and a 1967 Sea Ray boat with a Mercruiser (Chevy II 4 cylinder) engine. I routinely add a “lead substitute” and run both car and boat on premium — even though my GTO is a factory 400 cubic inch V-8 with a two-barrel carburetor and my boat is a 153-cubic-inch, four-cylinder engine with a two-barrel carburetor. What is the name of that additive that you spoke of recently in the newspaper?”

Halderman: The lead substitute is good for the valves in the head. The oil needs to have additional zinc to protect the camshaft and valve lifters from wear. Look for a zinc additive at most automotive parts store. It costs about $10 so that increases the cost of an oil change. Most engines built before 1990 may need to use this additive. There are several brand names of zinc additive including:

• Real Lead

• ZDDPlus

• Lucas Zinc plus

• Rislone Engine Oil Supplement

• Hy-Per Lube Zinc

Oil labeled “racing oil” can also be used as these oils often include the needed level of zinc. The zinc was removed from engine oil starting about 2004 and is still dropping as the newer engines need to meet ever-increasing emission standards. Zinc in the oil can get past the piston rings where it can then travel out the exhaust and into the catalytic converter. The zinc can harm the converter, which would cause an increase in exhaust emissions. A zinc additive is not needed nor recommended for engines newer than 1990 that use roller lifters instead of flat-bottom lifters. If in doubt, ask a knowledgeable technician, shop or dealer.

James D. Halderman is an ASE-certified master technician, a member of the Society of Automotive Engineers and the author of 12 textbooks. Submit your questions to Halderman via e-mail at jim@jameshalderman.com or follow him on Twitter @jameshalderman, or write him in care of: Wheels, Marketing Publications Department, Dayton Daily News, 1611 S. Main St., Dayton OH 45409.

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About the Author

James D. Halderman