01 May Why You Should Use Racing Oil When Breaking in a Rebuilt Classic Car Engine

The warm months of spring and summer are when it’s time to bring out classic cars, which often have maintenance and modifications that were completed over winter. If you have a classic car that’s undergone the major work of a rebuilt engine, think carefully about what oil you’ll put into the new baby.

Consider using racing oil, at least at first, as you break in your classic car’s newly rebuilt engine.

Motor Oil Has Changed Over the Decades

As automotive technology has progressed, significant changes have been made to both conventional and synthetic motor oils. Today’s oils are generally made for more efficient and hotter engines than those of yesteryear.

There are significant differences in motor oil if you just go back to the 1990s. Should your classic car before then, the differences in what oil it’s designed for and what’s commonly available will be immense.

Current Motor Oils Have Much Less ZDDP

One of the biggest changes is the large reduction of ZDDP that’s in the formulas of today’s oils.

Zinc Dialkyl Dithiophosphate is an anti-wear additive that’s zinc-based. Its physical properties make the agent effective at controlling corrosion and oxidation, and it was commonly included in oils and greases.

ZDDP was specifically reduced in modern motor oils because it causes problems with catalytic converters. The zinc and phosphates in the additive coat a converter’s active substrate, which can reduce the converter’s life span.

In accordance with Environmental Protection Agency regulations, American Petroleum Institute Guidelines, and general concern for catalytic converters, virtually all oil manufacturers have lowered the ZDDP in their various oils.

Older Engines Were Made With ZDDP Oils

Before 1970 (when the Clean Air Act was passed), engines were designed with the expectancy that owners and mechanics would be using oils that had ZDDP. The entire engine would be well-lubricated, and there usually weren’t catalytic converters to worry about.

If you’ve rebuilt a pre-1970 classic car with an authentic engine design, the lack of ZDDP is particularly an issue when breaking in the engine. Without multiple oil changes already thoroughly lubricating all engine parts, you need complete lubrication throughout the engine.

That’s what ZDDP provides for classic car engines. The zinc-based compounds in it will provide faster and more thorough lubrication for your engine.

Racing Oil is an Effective Alternative

Racing oil made for modern cars tends to have sufficiently high levels of ZDDP, and thus is generally a suitable alternative to old engine oil when you’re breaking in a classic car. Racing oil is made for cars that need to function at peak performance, and thus provide fast and complete lubrication.

A modern racing oil will quickly ensure your classic car’s rebuilt engine is properly lubricated and protected against unsuitable wear. You might change to a different oil that’s more suited for storage later on, but racing oil is an excellent choice for the initial break-in period that you’ll have this driving season.

Check out the selection of Amsoil racing oil before you finalized engine preparations and take that first drive of the year here.