Just bought this wonderful beast of a truck and got it back on the road (had brake issues). With that coming to a close I need to do a complete fluid change. Seems Mercon V for the transmission and typical gear oil (plus friction modifier) for the diffs. What about engine oil though...? I have no idea what the mileage is on the engine, but its likely 230k-260k (the odo is broken and I'm guessing based on stickers and the previous owner comments). If it matters at all, I'm also using Diesel Kleen as a fuel additive. I just want to get tons of life out of this engine so give me your best recommendations!