Most of the people think why mechanic asks to put oil in petrol (Gas) tank even when there is side tank available (Yamaha Motorcycle).
We have to understand deeply the process of this
Always remember that two stroke Engine like Yamaha motorcycle or any other motorcycle does not have a proper lubericant function like four stroke motorcycles or engines. Even if we do put oil in engine and in its side tank still the engine does notget the best lubrication as four stroke engine. in a result the two stroke engine not only gets hot quicker but engine does require overhauling after some time. Now, because engine gets hot faster and piston head starts expending it needs some thing to keep the movement of piston head normal and and to decress heat in cylnder chamber we add oil in petrol. The oil in petrol helps the piston head to move easily through the chamber and keeps the cylinder head cool. You amy have noticed that the pump to squeez oil from side tank in yamaha not properly works after some time that also cause engine overheat. The important thing is that a proper quantity should be maintained while adding oil into petrol unless your motorcycle start missing. This is the main advantage four stroke engines have on two stroke engines. Four stroke engines last long but two stroke engines require lot of expence on its overhauling and putyting seprate oil for engine cooling.
I hope you all now understand the basic function of adding oil in petrol tank.
If you still need information on two stroke engine you can write me at