[Shop-talk] Oil grade selection

[Doug Braun]

Last spring I had to replace the head gaskets on my
'98 Subaru, and I had a chance to inspect the cylinder
walls.  Even after 125k miles, I could still see the
original honing marks all around the cylinder walls,
even in the regions where the greatest wear occurs.

Also, when I checked the valve clearances, none of the
intake valves needed any adjustment.

You'd never see these things in an older engine!

Doug

--- David Scheidt <dmscheidt at gmail.com> wrote:

> My buddy the tribologist (he's got a PhD in
> lubrication, and designs
> oiling systems for jet engines) says use what the
> manufacturer says.
> Many modern engines have insanely close clearances
> (some are so tight
> that the max wear limits are less than the assembly
> tolerances of
> twenty or thirty years ago!).  If the engineers say
> they want 5W oil,
> there's a reason.