I got a few cars in my stall that I maintain, and now they have all had Pennzoil Ultra in them a couple times at least per engine. Various grades (5w30, 5w20, 0w40) and different vehicles with mileages ranging from 34k miles to 165k miles. One thing I noticed with all the vehicles is when I change the oil at 5k mile OCI - it always comes out dark red. Fuel dilution? Maybe, but the Ultra is the only oil that does it. No other oil (Mobil 1, Valvoline Maxlife FS, Castrol Edge) has ever done it. All other oils were either caramel color or dark dark brown, almost black. So why do you think Ultra becomes dark red instead of brownish like other oils? It just grinds my gears a bit hehe. And again - different viscosities, different vehicles, same used oil color after 5k miles.