by TS2Fifty » Fri Jul 25, 2008 5:33 am
Well you learn something new every day, I'd have thought that the higher quality oil the better. (The only exception being not to swap from "low ash" oil to non-additive type and back, which supposedly allows deposits to break free & get into bearings, and I doubt that's your problem.)
As it happens, I run Carlube low ash oil (very cheap, 99p 500ml!), at 30:1 to protect the main bearings, & that works fine for me. If changing oils doesn't sort your problem then it might be worth a plug chop as long as you keep an eye that it doesn't run too hot in your climate, as I'm in not-so-hot England the hotter plug might be too much for the piston's liking.
As for the mileage, I'd be surprised if the engine's loose enough to make full power just yet so that might be an issue still.
EDIT-: Just thinking about it, the carb. needle position is set higher (richer) to run the engine in & needs taking to the middle notch when done - which notch is yours set in?