My guess,front crank seal.My first gen1 3.0 blew two seals a few years back.First one was while running 15-40 oil with temparature at -15f.A year later wife ran the kids to school at -22f with 5-30 conventional oil lost 3qts in two miles.Front seal is on oil pump,small seal suseptable to blowing with thick oil.Installed second seal on that Monty with indian head sealant on outer surface and ran semi synthetic oil especially in winter never failed again.My LWB I drive now i've done the same with new seal and run 5-40 Shaeffers synthetic in the winter.6000 miles since October only down 1/2 qrt pretty good for 183k.