Two-stroke oil (also referred to as two-cycle oil, 2-cycle oil, 2T oil or 2-stroke oil) is an engine oil intended for use in two-stroke engines. Since these lightweight engines do not feature oil sumps to collect and recycle oil like 4 cycle engines, oil must be mixed with the petrol fuel, for distribution throughout the engine for the purpose of lubrication. The two-stroke oil is ultimately burned along with the fuel resulting in exhaust emissions such as blue smoke and a distinctive odor.
The oil base stock is either petroleum, vegetable, semi-synthetic or synthetic oil and is mixed with petrol/gasoline at a fuel:oil ratio ranging from 16:1 to as high as 100:1.
Engine Original equipment manufacturers (OEMs) introduced pre-injection systems (sometimes known as “auto-lube”) to engines to operate from a 32 : 1 to 100 : 1 ratio. Oils must meet or exceed the following typical specifications : TC-W3TM, NMMA, [API] TC, JASO FC, ISO-L-EGO.
Comparing regular lubricating oil with two stroke oil, the relevant difference is that two stroke oil must have a much lower ash content. This is required to minimize deposits that tend to form if ash is present in the oil which is burned in the engine’s combustion chamber.