Ok here goes on an oil problem. I bought a Hydro drive cub and first thing, I changed all the fluids. The oil in the hydro was black but not stinky. Ran the tractor around for a couple of minutes and the new oil is now black again. I guess this means that I will need to change it several times till it stays clear. The question is...At $11.oo ea.qt. I do not want to change this too many times. Filter the oil? Didn"t do a thing. Ran it through coffie filter etc. Can I use some type of chemestry that you mix in to the oil and it will settle out the carbon and or crud? I have heard of the stuff they use in water treatment and also for bio fuel clearing. What do you guys think. Thanks Jeffcat