Hmm lal godha HP du 20w40 oil edhu actually 4 stroke engine oil. 2T oil kintha 20w40 du viscosity jasthi erathe so petrol jothe e oil mix 2t oil astu proper agi agalla. Advantage 1. Slower speed alli lubrication channag erathe Disadvantage 1. Reduces the burning capacity of the petrol hence performance eralla. 2. Increases the exhaust smoke due to the fact that 20w40's burning point is higher than of 2t oil