Synthetic 2 stroke engine oils are today the best oils . All lubricate very well. Some do not burn as well and leave exhaust deposits, some are very clean and have little deposits or smoke. Penrite full ester synthetic , Silkolene comp 2 are great oils for slower riders learning, as they are clean. Smaller engines with low volume crankcases now are using 60 to 1 ratio, and this works very well. Caster synthetic type oil smells great, lubricates well, but is quite dirty inside the engine, dirty,sticky exhaust deposits, not ideal for powervalve engines, and the oil can separate from the fuel in the fuel tank and carby, if not used with in 2-3 weeks. The fuel oil goes stale very quickly. Will one oil make the difference of winning or loosing a race? Using Caster, take care to regularly clean fuel and exhaust and inside engine parts, and drain and use fresh fuel and oil.