Genos sells kits, that's where I get mine, very inexpensive. I do a sample with every oil change, diff change, transmission change, xfer case, etc. Since I do my own maintenance, I am still saving money over the stealership AND also getting good information and an outside record of the work I perform. I just catch in the drain stream, easy as anthing else except a tap on the bypass filter. If I was having any injector problems and beginning to have fuel seepage into the crankcase, the oil testing would give plenty of advanced notice. Also, if I had any fuel system problems I plan on taking a sample of my fuel before going to the dealership. Too many claims of contamination causing a warranty denial, I'll have the proof in hand with sampling results, that should clear anything that could be used as an excuse by the dealership and also expedite correct repairs.
CD