Automobile(s): 1991 Sedan deVille 4.9L/1994 Lincoln Town Car 4.6L
Chatham, Ont., Canada
In my two Deville's I've used Penzoil, Valvoline, and the Shell Rotella. Since I've switched to Shell gas because of the Top Tier recommendation, I figure the Shell oil is good too. But since any oil I've seen conforms to 'OEM specifications' I don't think it makes a difference if you change every 3k miles like you're supposed to. Synthetic oil may hold its viscosity longer, it costs more so there really isn't any savings. And since 4.9's don't rev beyond 4000 rpm, I don't think synthetic is needed. Just use the Shell stuff.