I have just bought a honda trx 420 quad and the clutch has started slipping. Iv been told to change the oil which I did and when I put in castrol 10/40 (1 litre) it ran tidy (for 20 minutes) after giving it a little run I brought it back and went out and bought another 2 litres of 10/40 car oil and now the clutch is slipping so much the bike wont move. Does anyone know if iv used the wrong oil which it seems like I have or if I have uses too much oil? Any info appreciated