Place your A.T.V. on a level surface and in park. Warm the engine up for a few minutes at idle. Loosen and remove the drain bolt at the bottom of the crankcase. If your engine is dry sump, loosen and remove the oil reserve tank drain bolt as well. Dispose of used oil in a proper manner. Tighten the drain bolt(s) to factory spec. If your machine has an oil filter, remove and replace it. It may be that your filter is washable. Fill your machine with oil to factory spec. Start your machine and check for leaks.