how much gear oil is needed and what grade for a 92 climber 280? i have a funny grinding noise from the engine as if the kickstart is being engaged when running. starts and rides perfect so dont think its anything major. was in a bit of a sorry state when i got it. so possibly may just need an oil change. now running it at 50:1 as previous owner told me 70:1 so decided to play on the safe side. any help including a manual would be hugely appreciated. thanks in advance guys