I am new to Polaris. I know nothing about them. I just bought a 2005 sportsman 90 2 stroke for my son. Can you guys give some advice on what to do and make this things work for him for a couple years to come. I know nothing about maintenance or any thing about it. I checked the front brakes tonight and it needs new shoes on the front. What about oil? Is there just trans oil I should change. Any type of engine oil I should use? I just know Honda's? Do they have engine oil? Or just oil for the mix since its 2 stroke. Plus does the trans have a curtain oil i should use. The guy I bought it from told me he just put a new chain and new front and rear sprocket on it. It looks new. It runs great. I just want to change all the fluids out and start with new since I don't know the quad. I know Polaris will say to use there brand of fluid but do I have to use theirs or can I just use a curtain kind that meets spec. Thanks for any reply's. I also notice a little window for fluid level on the side of the engine. Is that transmission oil or something.