You just answered your own question. Poor oiling to the rockers will only be
> enphasised with a heavier w oil. 15w40 is a heavier oil than straight 30 at
> operating temp.
The oiling problem happens when you start the engine cold. For some reason the oil takes a very long time to get to the rocker arms. Chevy may have fixed this later on??? The first two years the 6.2 had rocker shafts and what looks like cast iron rocker arms with a bronze bushing where it rides on the shaft. From 84 on they have stamped steel rockers.
Al
>
> > The book emphasizes that 30 weight is to be preferred over 15W40 (the
> > manual's second choice) when temperatures never go below freezing, and
> > yet your comment about the rockers gives me pause. I'll go with 15W40
> > unless someone here convinces me otherwise.
> >
> > Warren
> >
> > > >
> > > Amen. Use what the book says. I would use multigrade oil, whatever
> > > weight the book says. Your 6.2 has a problem getting oil up to the
> > > rockers. Heavy oil will make it worse.
> >
>
>