Traditional New Oils And Old Cars Don’t Mix


By Mark D. Sarine

Have you heard about the Zinc problem with modern motor oils? Many classic car owners and racers have experienced camshaft failures due to modern motor oils. Even worse, be prepared for the zinc to change in motor oils again later this Fall.

If you’ve not had the pleasure of having your camshaft go flat due to modern motor oils, consider yourself very fortunate. As an owner of an engine parts warehouse, I’ve seen hundreds of perfectly good camshafts ruined by modern motor oils. So when I read about the new API SN motor oil coming out this Fall, I started talking to the engine builders we supply parts. The engine builders all said the same thing – car owners don’t much know about these modern motor oils and the problems these oils create in classic cars and race cars. Knowing about the Cruise News, I contacted Mike to see if he could help us spread the word – modern motor oils are not good for your classic hot rods and race cars.

Here’s the facts:

Zinc or ZDDP as it is commonly referred to in motor oils is a type of chemical called Zinc DialkylDithioPhosphate, and Zinc has been the most common anti-wear additive used in motor oils for the last 60 years. I just call it Zinc because it is easier to say and spell.

Zinc is a remarkable chemical that protects engine parts from metal to metal contact under heavy loads. Zinc works by creating a film on the iron and steel parts in your engine. Unfortunately, Zinc also creates a film inside modern Three Way Catalytic converters. This Zinc Poisoning limits Three Way Catalytic converter life to around 70,000 miles.

The Federal Environmental Protection Agency (EPA) mandates that car manufacturers warranty Three Way Catalytic converters on new cars built since 2004 for 120,000 miles.

To achieve this goal, the car manufacturers worked with the American Petroleum Institute (API) to create new, lower Zinc oils that allow Three Way Catalytic converters to live for 120,000 miles.

These new Lower Emissions oils have extended catalytic converter life, but they have shortened the life of flat-tappet camshafts.

Not long after these modern motor oils with less Zinc hit the market, we started to notice an increase in flat-tappet camshaft failures. At first, it was the race engine builders, so we shrugged it off as some new trick the race guys were doing that caused the problem. Then we started to see stock flat tappet camshafts going flat.

Things got ugly really fast. Every camshaft company started researching the problem. So did the Automotive Engine Rebuilders Association. Everybody wanted to know, why are cams going flat?

The answer was Zinc.

Lower Zinc oils work just fine in modern production car engines with overhead cams, and roller lifters. These modern engines don’t rev past 5,000 RPM.

Most hot rod and race motors have push rods, flat tappet lifters and rev beyond 5,000 RPM. These engines need motor with more “‘Zinc”‘.

The good news is that High Zinc oils are available.

If you have a classic car or race car, I highly recommend using the Joe Gibbs brand oils.
We have seen a dramatic reduction in camshaft problems when our engine builders started using the Joe Gibbs brand oils. Since Joe Gibbs Racing is a NASCAR team, they are on top of all the latest advancements in technology, and they have developed oils that work. I’ve seen used parts from Joe Gibbs Racing engines that look brand new (even with over 600 miles on them).

If you’ve not had any problems so far, consider yourself very lucky. Switching to a High Zinc oil before the new API SN oils hit the shelves is like an insurance policy against having problems.

We like selling engine parts, but I hate seeing good parts go bad – Especially when they don’t have to.