Well,
How stuck is it
You might try running an oil designed for diesel truck engines for
a thousand miles or so. More detergents in that, so you might
get a cleaning effect from that.
I'm going to try some Shell 5W40 Rotella Synthetic this winter in
my Buick. I figure I can probably go 10K miles with that stuff and
wont need to change it until spring. I drive about 2500 mi/month
or more in that car. At about $12-$13 for a 1 gallon jug it might be a bargain
synthetic as well. (Of course I don't know how synthetic it is.)
Mobil also makes a 5W40 called Devac 1 for over the road truck
applications.
I've heard the truck engine oils recommended before. Most have
S ratings as well (such as SL or SJ) in addition to the C ratings.
(FWIW, S ratings indicate appropriate for use in spark ignition engines, and C ratings indicate
appropriate for use in compression ignition engines.)
So if you can find a 5W30 or 10W30 (if you are not comfortable with 5W40)
it might be the ticket to cleaning out extra varnish in the engine.
HTH,
TB
