Warning: If You Have An Older Vehicle, Choose Your Oil Carefully
November 30th, 2007 Posted in Helpful Information, Technology

motoroil If you own an older car, you might want to think twice about the oil youíre using.

In order to comply with federal requirements that key emissions control components on new cars such as catalytic converters last at least 120,000 miles (previously, it was 100,000 miles) automakers have been pushing for reductions in an oil additive known as zinc dialkyl dithio phosphate (ZDDP), which contains phosphorous (as well as zinc and manganese).

The problem for late model emissions-controlled cars is that the phosphorous in ZDDP has been linked with premature catalytic converter failure - or at least, premature loss of converter efficiency.

But the problem for older cars with flat tappet camshafts - which means pretty much all cars and motorcycles built before about the mid-1980s, when roller camshafts began to supplant the flat tappet design - is that oils with low ZDDP levels can cause rapid premature wear, even failure, of flat tappet camshafts. In a nutshell, the ZDDP cushions the high pressure point between the lifter crown and the camshaft lobe, acting as anti-friction, anti-wear barrier.

Running without the ZDDP is almost like running without oil ó and with the same results.

Levels of ZDDP in commonly available mainstream motor oils - including big-name brands and high dollar synthetics - have been dropping or have been eliminated since the new emissions longevity requirements became effective with the 2004 model year.

Unfortunately, many hobbyists and owners of older cars and motorcycles with flat tappet camshafts are unaware of the changing formulations - and the threat low-ZDDP oils may represent.


The first thing is to determine whether your vehicle is equipped with a flat tappet camshaft.

If itís an American-brand car older than model year 1980 and the engine is either original or has been rebuilt to original specifications, the odds are virtually 100 percent certain that you have a flat tappet camshaft.
Itís also very likely you have one if your car is early-mid 1980s.
By the latter half of the í80s and into the 1990s, roller-style camshafts were becoming the norm - and you are probably safe. But itís important to be sure.

You wonít find information on the type of camshaft your vehicle has in your ownerís manual.

Youíll need to consult a technical service manual - or simply ask someone who is knowledgeable. The service manager at a dealership for your make/model of car ought to know - or should be able to find out.


There are still a few oils on the market that have adequate levels of ZDDP.

Valvoline VR-1 racing oil contains 1,800 parts per million ZDDP, according to Valvoline - 5 times the amount of other oils. It's also an excellent choice for older, non-emissions controlled engines with flat tappet cams that need ZDDP. At Bench Mark Works, we have switched our recommended engine oil for 1983 and older BMW's to 30 weight (winter) and straight 40 weight (summer) Valvoline VR-1 racing oil.

On our online store page, the following items can be found:
acc069--Valvoline VR-1 40w oil
acc069A-Valvoline VR-1 30W oil