Which motor oil to use is usually a subject of much debate and discussion. Some people have very strong brand loyalty, some base their opinions on what worked for someone else in the past, and others just figure “oil is oil”. Now that we are in the year 2017 there are some things you should know before choosing a motor oil.

there is no catalytic converter on your motorcycle

New Federal regulations led to the creation of a new oil standard that is intended to improve fuel economy, lower emissions, and extend the life of catalytic converters. The new standard is ILSAC GF-5* and API SN. The API˚is responsible for overseeing the standards for oil sold in the United States. While these new standards may be good for your new passenger car, it is not good for your vintage motorcycle. Triumph motorcycles along with other flat tappet automobile camshafts need more protection from oil than these new formulations can provide.

*International Lubricant Standardization and Approval Committee               ˚American Petroleum Institute

Zinc dialkyl dithiophosphate (ZDDP)

The most common antioxidant/ anti wear additive in motor oils is ZDDP. It works by forming a sacrificial film on the surface it protects, which is extremely important in preventing wear on tappets and camshafts. ZDDP has been found to harm catalytic converters, and more legislation has led to the reduction of this additive in passenger car oils. This means that the oil you buy at the auto parts store may no longer protect your engine. Any oil with the API SNSMSL  ratings along with ILSAC GF-5, or anything labelled ”energy conserving” or “resource conserving”  should never be used in a vintage motorcycle. There are however many oils on the market today with high levels of ZDDP, you just may not find them at your local auto parts store.

the government doesn’t care about your engine

Since the overall percentage of vintage vehicles on the road is so small, almost no consideration has been given to the owners of these cars and motorcycles by anyone in government. There is no money in keeping old vehicles on the road, it is considered a hobby and as witnessed with the “cash for clunkers” program the mentality is just about the opposite of how most vintage motorcycle owners think. No one cares if your cams go flat from bad oil or your vintage fiberglass tank turns to jelly from ethanol. It is up to you to keep track of what is changing and how it affects you.

what oil to use

There are plenty of specialized oils on the market today that are suitable for use with flat tappet cams and vintage motorcycles. They are labelled “RACING OIL” and carry no API rating or certification. Because racing oils are made for “off road use” they are not subject to the same restrictions and standards as passenger car oil, which allows the manufacturer to use whatever levels of ZDDP and detergent they find is best to protect your engine.  The brand we sell at the shop and use is PENNGRADE 1, although there are many other oils for motorcycle and air cooled applications available as well. PENNGRADE 1 is the best monograde oil we have found to be suitable for air cooled flat tappet engines that can withstand the heat in Southern California without degrading rapidly.

What viscosity should I use in my vintage Triumph?

According to the factory Triumph workshop manuals the following viscosity oils are recommended for use in the USA:

Pre Unit 500 1937-1949


Pre Unit 500/650 1950-1962

ENGINE OIL  (summer)SAE40  (winter)SAE30  GEARBOX SAE50  PRIMARY SAE20

Unit 350/500 1957-1970

ENGINE OIL  (summer)SAE40  (winter)SAE30  GEARBOX SAE50  PRIMARY SAE20

Unit 650 1963-1970

ENGINE OIL  (summer) SAE40  (winter) SAE30  GEARBOX SAE50  PRIMARY SAE20

Unit 650 and 750 1970 and up

ENGINE OIL  (summer) 20w/50  (winter) 10w/40  GEARBOX 90w  PRIMARY (same as engine)

As oil technology has progressed, some people prefer to use multi viscosity oils and synthetics in their vintage machines. Being that most of our customers are in Southern California there is no need for a cold weather oil. The “synthetic vs petroleum based oil” discussion evokes about the same response as the old “propane vs charcoal” at a bbq, so that will not be addressed here. Also for those that use “diesel oil” such as Shell Rotella T, please be aware that the EPA has recently changed the standards for diesel emissions and fuel, and there has been a reduction in the ZDDP levels in the API CJ-4 oil. There is a wealth of information out there and we would welcome you to do your own research.

in conclusion

Triumph motorcycle engines have what some machinists would consider to be huge tolerances. The engines were designed to be reliable and make power across a wide range of rpm’s. The factory recommended oil grades that would be best at the time these bikes were manufactured. Since the tolerances haven’t changed, the designing engineers’ oil recommendations haven’t either. The fact is that modern engine oil is very different from the oils of the past and it is much harder to find suitable oils to use in these machines.

PennGrade 1

“The Green Oil®” Franz and Grubb Engine has PennGrade 1 High Performance Oil in stock in the following viscosities: SAE 30, SAE 40, SAE 50, and SAE 20W-50, reasonably priced at $8.95 quart.Brad Penn Grade 1