This is for everyone that reads this.Anyone attempting to work on their own machine should own a shop manual. Why trust answers you get from strangers when you can have the answer to every one of your questions right in front of you. Would you rather spend $30 for a worth while investment, or spend over $500 when you make a mistake?Purchase a shop manual - even professionals use them.http://www.motocom.com/motorcycles/Always give year, make, engine size and model # when asking questions. We need all of that info to give an informed answer.2003 Kawasaki KFX400 - The oil tank has a dip stick.After draining the oil and changing the oil filter, fill the oil tank to the top line of the dipstick.Check the oil level with the dipstick resting on the threads (don't screw it in to check the level).Re-install the dip stick.Start and run the quad for a couple of minutes to let the oil circulate throughout the engine (the oil tank lubes every part of the engine).Turn off the quad and re-check the oil level - add more if needed.Kawasaki's web site recommends 10w40 approx 2qts.Use quality brand name 4 stroke motor oil.