First - Four stroke engines require more lubrication than do 2-stroke engines. This is do to the number of moving parts. Unlike a 2-stroke, a 4-stroke does not have the benefit of raw fuel and oil pumping through its crankcase for lubrication. A 4-stroke draws it's fuel in from the top of the cylinder by the down stoke of the piston. Lubrication is accomplished by blow-by at the BDC (bottom dead center) and run-down of oil through the lifter tubes. This oil must migrate to the bearings as well, therefore, volume is essential. (See disassembled 4-stroke -vs- 2-stroke below for comparision). Yes, despite the nonsense that some would try to get you to believe it's that simple.

Second - Wildcat recommends the lubrication package be totally synthetic. The use of synthetic oil is important in four stroke engines to prevent gumming and varnishing of the lifters and coking of the valves. Varnishing will occur on castor based fuels. This can lead to sticking valves, which will cause the valve set to get knocked out of time. Coking of the valves will cause improper seating of the valves causing a reduction in compression and incomplete combustion. Four stroke engines also have high exhaust gas temperatures and the use of synthetics greatly reduces carboning at the exhaust ports.

Third - Some fuel manufacturers claim that the number of moving parts in a 4-stroke is irrelevant to the oil content of the fuel, and they produce and recommend oil contents lower than that recommended by the engine manufacturers. Remember they do not provide the warranties for your engines they have no investment in your engine. Wildcat fuels meet or exceed the engine manufactures warranties of all common 4-stroke engines manufactured today. Because of the higher oil content, WILDCAT 2 & 4-CYCLE fuels can be run in any 2-stroke engine (except ducted fans) where a fuel with total synthetic oil is desired.

 

THE 4-CYCLE PRINCIPLE


The four steps (strokes) in a complete power cycle of a 4-stroke-cycle engine.

CLICK HERE FOR A COMPARISON OF 2 STROKE AND 4 STROKE ENGINES
 

[ A ]  On the down stroke, the intake valve is opened and the fuel/air mixture is drawn into the combustion chamber.

[ B ]  On the upstroke, the intake valve has closed and the fuel/air mixture undergoes compression.

[ C ]  Ignition takes place by means of the glow plug (not shown); the fuel/air mix explodes, and the piston is forced down for the second time in the cycle. This is called the "power stroke". 

[ D ] The exhaust valve is open and the piston moves up for the second time in the cycle, and the burned gases are expelled out through the exhaust valve into the muffler.