Oil Study


You should not be using many of the new oils in engines built before the mid 80's. Special oil is available for those engines and must be used or you'll burn the cam and lifters out.

The reason why is that most of today's oils are designed to be used in engines with a roller cam train. These oils have a "SM" API rating, meaning the ZDDP (zinc) has been reduced to 600 PPM. (PPM=parts per million)

It's a known fact

that "break in" oil needs 1500 PPM (0.15%) ZDDP. After break in, it's OK to use 1000 PPM (0.1%) ZDDP, on pre-roller engines.

    A summary of API ratings on oil is:
  • SH = ZDDP first reduced to less than 1000 PPM.
  • SJ and SL = ZDDP further reduced to 850 PPM.
  • SM = ZDDP now currently reduced to 600 PPM.
  • Note: do not overdose ZDDP as the extra zinc will cause bearing corrosion.

Lockhart Machine

recommends “Breaking In” an engine with “Joe Gibbs Break-In” oil.

After following Break-In procedures for approximately 30 minutes then draining Break-In Oil and changing oil filter, we have found the best lubricity is provided by using “Rotella T” non synthetic oil.

Understanding API

With the exception of some specialty products,

most consumer motor oils come labeled with a viscosity rating from the Society of Automotive Engineers (SAE) and a service rating from the American Petroleum Institute (API). We suspect most readers are familiar with both. But for any who are not, we’ve prepared this quick guide.

First we’ll explain the SAE viscosity rating, which is often also called the oils “weight”. Viscosity, according to Tim Wusz of Rocket Brand Racing Fuel, “refers to the ability of a type of oil to flow through a given size orifice within a certain time frame at a specific temperature.

The more time the oil needs, the higher its viscosity number. The numbers themselves—10, 20, 30—have no units but correspond to the viscosity grades established by the SAE.” The letter “W”, when it appears, indicates an oil that has also been tested at a low temperature and judged suitable for winter use.

“Some people balk at using low– viscosity oils like 5W20 or 10W30,” Wusz added, “but these lower viscosity oils help to reduce friction in engines, [and are] easier to pump, which allows for more horsepower or better fuel economy. Today’s engines are built with tighter bearing clearances and tighter rod side clearances compared to 20 –plus years ago. With these and other changes, these engines can be very happy with oil that was previously considered too thin.”

In the API service ratings, “S” stands for “service” but refers to service in gasoline – fueled engines, while “C” for commercial indicates a type of oil formulated for diesels. “The program certifies that an oil meets certain OEM quality and performance standards,” explained Torco’s Ernie Soliz. “this has a lot more to do with additives.”“To get the API rating,” added Wusz, “the oil must pass a series of high– and low– temperature engine tests to evaluate its ability to provide wear resistance, sludge resistance, varnish resistance, etc. Any oil that has passed these tests and earned the rating is considered equal to all other oils that have earned the same rating. So don’t be misled by advertising.”

The API claims that all rated oils are backward– compatible; for example, SL– rated oil should be safe for use in any gasoline automobile engine manufactured in 2004 on back to the dawn of the industry. But according to Lake Speed JR. of Joe Gibbs racing, ZDDP content was first dialed back with the SH rating, then limited to less than 1000 PPM with SJ. SL reduced it to 850 PPM or less—“and that’s when racing cams started to fail” said Speed, who added that with the SM rating and ZDDP content of 600-800 PPM, “camshaft failures skyrocketed.”

api zinc rating