The promise of synthetic oils is finally being realized as today's synthetics have superior film strength, can tolerate temperature extremes from -60°F to more than 500°F, do not leave carbon deposits and maintain their viscosity even on very cold days.
With one notable exception, my experience with synthetic oils in two-stoke engines has been positive. My first experience came as a teenager flat tracking a Bultaco motorcycle. The 125cc Bultaco engine had a high output for its time (24 hp at 10,000 rpm). The center bridge on the exhaust port had to get the best possible lubrication to prevent piston seizure. Back in the sixties there was only one synthetic oil- Racing Castor oil.
Commonly known as "bean oil," it was extracted from natural plant oils. Large molecules provided great film strength, and the rumor was that the oil was attracted to hot surfaces, rather than just burned up. To seizure-prone racing two-strokes, this meant reliability and race finishes. Just the sweet smell of the exhaust was worth the extra effort mixing it.
Trouble was the stuff did not mix well with the gas, and after a very short time would separate into big globs of oil. These globs would then get stuck in the jets, leaving you with a misfiring machine.
To get around the problem, we would wait until shortly before the race was to start and then throw my mother's hand-cranked blender into a bucket of the fuel and oil mix, and whip it up real good before we put it in the tank. It was then good for a few hours. After the races, we emptied out the tanks and float bowls, and cleaned everything to make sure there were no oil globs left. As long as this routine was followed, the high-strung Bultaco engine ran without failure.
The mix did leave a good amount of deposits. Engine teardowns to clean combustion chambers, piston crowns and ring grooves became a regular maintenance schedule. The stuff is still around today in a finer processed and de-gummed form. Many racers still swear by it, especially go-kart drivers with air-cooled engines revving over 14,000 rpm. Good stuff in the summer, and the sweet smell always makes me smile, it's the smell of real racing.
The second try at synthetic oils was not a success. This was not due to a failure in marketing or lack of performance. Union Carbide introduced synthetic oil formulated from alcohol. They put on a remarkable marketing blitz, with full factory support at the races. The main marketing manager was a likable and fun person with a huge handlebar mustache. The oil was nicknamed "rabbit oil" from the slogan- "Run with the Rabbit."
For a while it seemed as though everyone was running in the rabbit pack, but by the following fall the rabbit pack was not exactly running any more. Most of the racers who had used the stuff got a nasty surprise when they tried to start up their engines in the fall. The crank would not turn as all the bearings had rusted solid to the crank. This was an unfortunate side effect of the alcohol, which was used as a base stock.
Complaints were numerous, cranks had to be replaced and the oil was pulled off the market. This left everyone skeptical about synthetic oil, and drivers returned to petroleum- based products. In the meantime the petroleum oils had gone through a period of development where other additives, among them zinc, had been added. The zinc additive improved film strength and allowed higher mix ratios in outboards. Outboard oil was soon the hot set-up for racing any two-stroke.
Developing a good synthetic oil was a costly process. If it was not for the U.S. Air Force, we might still be using petroleum-based oils. The military's new jet engines required lubricants that could operate at a very low temperature in high altitude, yet still tolerate the high temperatures inside the engine. Since this was a high priority for national defense, the government spent whatever it needed to develop the new lubricant. The result was a pure synthetic lubricant, with di-ester as a base stock. The di-ester-based oil was first introduced in two-stoke racing engines back in the seventies.
Al Amatuzio, the founder of AMSOIL, was a retired Air Force pilot. During his time as a fighter pilot, he had been favorably impressed with the synthetic lubricants used in jet engines. Why not use this oil in regular piston engines, he often questioned. Cost was one good reason; the lubricant was expensive to produce. Back in the sixties the U.S. Army also got involved, mainly because it needed a lubricant that would still work in trucks at -60°F. This helped to commercialize the synthetic oil.
When Amatuzio retired from the Air Force, he founded AMSOIL and set out to market the synthetic lubricant. Back in the late seventies, we were fortunate enough to have our Sno-Pro racing team sponsored by AMSOIL. We enjoyed our time with AMSOIL as they spent enough money to get the job done right, including promoting Sno-Pro oval races at the Superior, Wisconsin fairgrounds.
At a time when recommended petroleum based oil mix ratios were between 16-to-1 or 25-to-1, AMSOIL recommended using a 100-to-1 mix with its racing oil. This was the first time we used it at 100-to-1. Obviously, we wondered if the engine would seize. Instead we picked up throttle response, acceleration and top end power. The only problem we had was reading spark plugs, because hardly any oil would deposit on the plug. With Tim Bender, Bobby Donahue, Doug Hayes and Fran Higginbottam as drivers, and full AMSOIL backing, our team notched many major race wins against stiff factory competition on the Sno-Pro circuit.
To get its name in the public's mind, AMSOIL sponsored many major teams in Stock Cars, Indy Cars, NHRA drag racing, boat racing and snowmobile racing. At the same time, they aggressively expanded their production facilities and research labs. These racing programs came to a grinding halt in the early eighties as interest rates skyrocketed. Amatuzio was forced to use the monies designated for racing to pay for the huge factory expansions.
That was then. Once again racing is a priority at AMSOIL. Today they sponsor the Scheuring team in snocross that notched great wins over the factory teams at Duluth, Minnesota, right in AMSOIL's own back yard. While AMSOIL was the first in pioneering di-ester-based synthetic oils for two-strokes back in the seventies, the advantages are now recognized by a large number of manufacturers.
According to Joe Horstman, factory manager at Klotz lubricants, di-ester is a natural for mixing with gasoline. Diester based oils will mix directly with other petroleum- based oils and also with gasoline, so there is no need to clean out the system when adding the synthetic product.
Most synthetic oils are now formulated to use in a 50-to-1 mix ratio, which works well with oil-injected engines. The big advantage with synthetic oils is their multi viscosity and tolerance for temperature extremes. The oil does not thicken when the temperature dips into deep freeze. Di-ester-based oils continue to function at -60°F, and at the other extreme can be made to take 500°F.
Petroleum-based stocks start to oxidate rapidly around 250°F. With additives, the current upper limit hovers around 300°F. The synthetic lubricants can normally be made to withstand 500°F, and with more refinements the upper limits can be pushed to 700°F.
This tolerance for higher temperature means less deposits and more lubricant left on bearing surfaces. Klotz moved into developing synthetic oils to eliminate the problems occurring with petroleum oil: burning, carbon deposits, plug fowling and scuffing. In two-stroke engines, the area around the exhaust port timing edges gets very hot. Synthetic oils with high temperature tolerance and better film strength offer much better protection against piston scuffing than petroleum- based oil, particularly in engines with multiple exhaust ports and hot bridges.
With high temperature tolerance comes less deposits. Petroleum oils start burning sooner and deposit carbon in ring grooves, on power valves, on spark plugs and in exhaust systems. Clean burning synthetics leave the ring free and lubricated, the spark plugs free of deposits and power valves operating correctly longer. They also drastically reduce deposits in the exhaust system.
Superior film strength is a great advantage when it comes to synthetics. The moving parts in an engine are supported by a film that is only a few molecules thick. In cases of high pressure and excessive pounding, some breakdown of lubrication occurs, causing metal-to-metal contact and fusing of engine components. This is critical in two-stroke engines with the line and point contacts of needle bearings and ball bearings in the crank.
Conventional oils are dynamic in terms of their lubricant properties, this means they need motion to create a protective film. Synthetic lubricants need no motion, they have such a high film strength that they actually roll with the engine parts and resist shearing of the film from the minute you start the engine.
With new emission requirements, fuel will be injected directly into the cylinder. With no fuel mix to cool the crankcase, good oils are needed to lubricate the cranks at higher temperatures and leaner oil ratios. At the moment, synthetics offer the best high temperature protection for these future engines. If you can add more performance, less maintenance, cleaner engines and better fuel mileage, what's not to like about synthetic oils?
This story ran in the February 2004 issue of American Snowmobiler magazine