HT4100 4.1, 4.5, 4.9 Discussion, 4.9L Oil Consumption in Cadillac Engine Technical Discussion; Originally Posted by Tailfin
Maybe a happy medium here...like 15w-40?
That's too viscous at operating temp....
Automobile(s): 1991 STS, 1992 Fleetwood, 1987 Maxima wagon
Bay City, MI
Re: 4.9L Oil Consumption
Anyway, back on topic... '91 STS (almost 94K) goes through about a quart every 600-800 miles and I've seen black smoke in the rearview mirror occasionally when I give it the beans. '92 Fleetwood (114K) has needed nothing between changes. 5w30 during winter and 10w30 during the summer.