F ORUM FAVOURITES

Ask a keyboard warrior if you must, but here’s the word of an expert...

Can mineral, synthetic and semi-synthetic oils be mixed together? “All of those products are mineral based. So long as the correct grade is used there’s no problem mixing them together. That applies to both pre-mix and injection oils but don’t use a pre-mix oil in an injector system because the viscosity is likely to be too thick.”

I want to try one of the old school castor oils, is there any special preparation needed? “Castor and mineral oils react badly together and will form a thick gel. When changing a fuel system from one to another it should be flushed thoroughly with neat petrol.”

Could a pre-mix oil be used in an injector system? “It’s critical that only specially formulated oils are used in an injector (‘autolube’) system. There’s a very small amount of time and space in which the oil can be injected into the fuel mixture. Using a thicker oil runs the risk of blocking the mechanism with potentially catastrophic results. Conversely injector oils are fine to use in pre-mix tanks.” Does ethanol in petrol affect two-stroke oil? “I’m not a petrol expert so can’t comment on the other effects of ethanol but it has no impact on how a rider should use two-stroke oil.”

Is using cooking oil as an emergency substitute just an urban legend? “I’d say so. In an emergency I’d do whatever necessary to get some two-stroke but if there really was no alternative, multigrades should be completely avoided as they have potential to cause damage very quickly. The old two-stroke oils were roughly 20W 50 so that would be my first choice but even then I’d be prepared for a drop in performance, a very smoky engine and fouled plugs at best. The injector system should be bypassed by premixing in the tank and the engine ridden very gently. Once a two-stroke stockist is located the tank should be flushed thoroughly. The chances of damage are so high that personally I’d pay for a taxi to the nearest motorcycle shop!”