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 2020 there are some things you should know before choosing a motor oil.
There is no catalytic converter on your motorcycle
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 oil standard created in 2010 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
Its going to get worse
The ILSAC and API have created a new GF-6 oil standard to begin May 1, 2020 to protect turbo engines in passenger cars from low speed pre ignition. This will also replace the current GL-5 standard. Also GF-6B will also be introduced in 0W-16 only. These oils are both wildly different than the oils your motorcycle was designed to use.
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 SN, SM, SL ratings along with ILSAC GF-5, GF-6, GF-6B 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 oil 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:
|MODEL||ENGINE OIL (summer / winter)||GEARBOX / PRIMARY|
|PRE UNIT 500 1937-49||SAE40 / SAE30||SAE40 / SAE20|
|PRE UNIT 500/650 1950-62||SAE40 / SAE30||SAE50 / SAE20|
|UNIT 350/500 1957-70||SAE40 /SAE30||SAE50 / SAE20|
|UNIT 650 1963-1969||SAE40 / SAE30||SAE50 / SAE20|
|UNIT 650/750 1970-UP||20W/50 / 10W/40||90W / 20W/50|
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 and CK-4 oils. There is a wealth of information out there and we would welcome you to do your own research.
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.
Our favorite oil for vintage Triumphs is PennGrade 1. It can be found in SAE30, SAE40, SAE50, SAE60 weights along with 20W-50 Motorcycle oil. This oil has a long history in racing and is still made from 100% Pennsylvania grade Crude Oil.