The person that I bought my GMC had always used Quaker State 30WHD in
the engine. When I replaced the valve cover gaskets there was no sludge
or build up in the engine. Looked brand new inside.
J.R. Wright
>
> To All:
>
> Running 455, changed to Mobil 1 15w50 2 oil changes back, have used 12 qts
> oil in 3300 miles, changing oil tomorrow, have been advised to go to 40w HD;
> previously used Castrol 20w-50 - used approx 1 qt per 300 miles; 80,000
> total miles, alleged engine overhaul 15,000 miles back; no apparent leaks, no
> smoke.
>
> Have 2 cases Pennzoil 40w HD on hand - should I use it? All I've heard is
> that it and Quaker State are parafin based and will sludge your engine.
>
> Any opinions or comments??
>
> Lanier
the engine. When I replaced the valve cover gaskets there was no sludge
or build up in the engine. Looked brand new inside.
J.R. Wright
>
> To All:
>
> Running 455, changed to Mobil 1 15w50 2 oil changes back, have used 12 qts
> oil in 3300 miles, changing oil tomorrow, have been advised to go to 40w HD;
> previously used Castrol 20w-50 - used approx 1 qt per 300 miles; 80,000
> total miles, alleged engine overhaul 15,000 miles back; no apparent leaks, no
> smoke.
>
> Have 2 cases Pennzoil 40w HD on hand - should I use it? All I've heard is
> that it and Quaker State are parafin based and will sludge your engine.
>
> Any opinions or comments??
>
> Lanier