What type of oil do i use in my yamaha 125cc 2 stroke motorcycle other than that which i mix with the fuel?

You have oil in your transmission/clutch that needs to be changed every so often. I don't know the time period but probably 5 to 10 races! Or 5 to 10 tanks of gas. Check you owners manual for specifics of that bike! If you don't know where to put it, ask someone to show you. It will very hard to explain over the computer! Use motorcycle engine oil, not motor oil for a car and certainly not transmission fluid! Motorcycle oil is specially formulated to resist breakdown from the shearing that goes on in the clutch and resist foaming when going through the teeth of the gears in the transmission! Go to a motocycle dealer or visit http://royalpurple.com/motorcycle-oil.html A little expensive but good stuff!

Yes, on the clutch side of the engine there should be an oil fill plug for the crankcase. It should take 10w-30 or 10w-40. It may not need oil often but it's a good idea to check each time before you ride. As far as capacity or the oil change interval i'd check with the local dealer or repair shop. Hope this helps!