Ya can do dual filter thats great more filtering can't hurt anything, id recomend a fuel filter but an oil filter works just fine, I also use a wire filter to dump the oil threw before it goes in my 55 gallon drum just cuz depending on where you get it from there can be a lot of sludge in it the last place i got it i swear there was more sludge then oil so it would have clogged my filter right away had I not strained it firat