Choosing A 2-Stroke Oil
January 19, 2006
Filed under Tips
With burgeoning power output and increasing environmental considerations, proper lubrication becomes even more critical to the operation and longevity of engines.
The most important thing to keep in mind when selecting an oil is that engines require different grades and each owner must understand their engine’s needs and specs to choose an oil accordingly.
Oil provides a fluid cushion that prevents direct metal-to-metal contact, which wears the engine. But that is just the beginning of its functions.
Engine oil also contains an additive package to prevent corrosion and rust, which is essential for engines that sit idle for months in the off-season. Because two-stroke engine oil goes through the combustion chamber, it must mix with the fuel to burn as cleanly and completely as possible.
Spark plugs, rings, ports and exhaust valves must not be fouled with combustion deposits; and exhaust smoke must be minimized if not eliminated. Finally, oil should not cause unpleasant sensory effects, such as lingering odors or burning eyes.
Contemporary snowmobile engines — particularly the more sophisticated designs with variable exhaust valves — have specific lubrication requirements that differ considerably from motorcycle, marine and other two-stroke engines due to unique operational patterns and cold weather use.
All engine manufacturers set minimum lubrication requirements, and all the major snowmobile manufacturers sell their own brands of oil that are specifically developed by third-party vendors to meet their engine’s needs.
All of the major snowmobile manufacturers recommend exclusive use of their oil, implying that if you use something else, you may have trouble. But there are also a myriad of aftermarket oil brands available — each one claiming to be the greatest thing since chunky peanut butter. Who should you believe and why?
Let’s start with warranty coverage. Using oil that fails to meet the manufacturer’s operational criteria can definitely lead to problems — ranging from poor performance to outright engine failure. Also, using inadequate oil can void warranty coverage.
However, the Magnusson-Moss Act guarantees warranty coverage of any oil that meets the specifications for the engine.
So what should you do? First, consult the owner’s manual for information on your engine’s requirements. Then there are two basic choices: Use the manufacturer-recommended lube or get educated about two-stroke oil and make an informed choice of an aftermarket product.
Making The Choice
If you want to keep things simple, the choice is a no-brainer. You can’t go wrong using the manufacturer’s oil. After all, it was developed to meet the requirements of your snowmobile’s engine.
But what if you have an engine that has been tweaked to produce more power? Or what if you want a product that is cleaner burning, more environmentally friendly or less expensive than the manufacturer’s recommended oil? This is where it starts to get complicated.
First, rule out choosing oil on price alone. You have a lot of money invested in your snowmobile, so why would you choose one of the most important consumables required for the machine’s well-being based on price? Don’t be penny wise and pound foolish.
Now, what about other brands that claim they are better and will do amazing things for an engine? Be careful. There are snake-oil salesmen out there, and they are definitely looking for gullible snowmobilers. Then there are others selling oil that really isn’t appropriate for a sled’s powerplant, particularly the high-performance power-valve engines that are popular in snowmobiles these days.
Navigating The Certification Maze
Most general two-stroke oils are now formulated to meet the TC-W3 certification of the National Marine Manufacturing Association (NMMA) for boat motor use. Why? Because boats are the most common application. However, snowmobiles are not boats and have considerably different lubrication requirements.
Boat engines do not have variable exhaust valves. Other marine applications include a lower specific output, unchanged throttle positions for lengthy periods of time and the discharge of exhaust directly into the water instead of the air.
There are also other factors involved, including typical ambient air temperature, type of engine cooling and even oil storage considerations. So beware: It may say snowmobile oil on the label, but it’s still boat motor oil inside if TC-W3 is the only certification rating it meets.
Many high-quality TC-W3 oils work just fine in many snowmobile engines. But lesser quality TC-W3 oils do not provide adequate lubrication and protection for some snowmobile engines. None of the three North American snowmobile manufacturers specify use of TC-W3 oil in their owner’s manuals. Bombardier pointedly tells its customers not to use it, recommending API-TC rated oil instead.
The American Petroleum Institute (API), the Japanese Automotive Standards Organization (JASO) and the International Standards Organization (ISO) also evaluate and rate two-stroke oils. The latter two have rating systems that were developed partly to deal with the specific needs of snowmobile engines.
The most recent API rating for two-strokes is TC. Although the API no longer maintains this as an active standard, it is still an industry reference.
Until recently, the top JASO oil rating was FC, and you will continue to see this listed in many places. But the tougher FD rating is now available, and some companies upgraded their products. The JASO-FC standard is also important because it includes a test to specifically measure exhaust smoke. So JASO-FC and the subsequent FD test are the key for visible exhaust emissions. JASO FB and FA offer less, but still acceptable, performance.
ISO-L-EGD is the top European two-stroke standard, with EGC and EGB as lower performance levels. A plus sign after the letters (EGD+) means that the rating is significantly exceeded.
Winter Use Really Is Different
The pour point is another key reason why it makes sense to choose oil developed specifically for snowmobiling.
The pour point is the lowest temperature at which a fluid will move due to the force of gravity. Although the pour point does not indicate a minimum temperature at which the engine will start, it does tell us something about the physical characteristics of the oil at a low-temperature startup, which is important because startup is when most engine wear occurs.
Two-stroke oils developed primarily for boat motors typically have pour points that are significantly above the deep-freeze temperatures snowmobiles endure. Most oils that are formulated specifically for snowmobiling include ingredients that drop this statistical measure to at least minus 40 degrees.
Most knowledgeable users now prefer full synthetic oil for racing and other high performance applications. Synthetic blends are increasingly accepted as less costly alternatives for both competition and trail use.
An accepted technical definition of the term “synthetic” oil is often debated. For starters, synthetic oils can be built with a number of different base compounds. The introduction of synthetic blends, which combine significant quantities of natural and artificial base stocks, has added to the confusion.
The diester-based full synthetic oils, including Spectro Syn-Sno and Castrol R2 Snow, are renown for great lubricity, wear protection and ability to mix with gasoline and alcohol. Ester-based synthetics aren’t new. They’ve been used in race sleds, race bikes, racing saws and other performance two-stroke applications for more than 30 years.
Though they tend to be expensive, these products also offer other benefits including virtually smokeless and odorless operation, a low pour point, no ash residue and the ability to keep power valves clean.