I understand there is a difference between "Ashless" and "low ash" 2-stroke oils depending on the type of detergent used. Does anybody know which type is specified for the HT engines? Seems to me that with the low RPMs and poor tuning an ashless type would be best for a minimum of deposit build up. Is this correct? What brands or types of oil are ashless? I am considering running a mix of racing castor 20% and ashless regular oil 80% any recommendations? Are Outboard engine type oils ashless? incidently why does it say to not use these oils in other engines?