On Thu, 18 Jan 2007 13:34:38 -0500, clare at snyder.on.ca wrote:



Also, the legendary "coking" problem on Toyotas and Chryslers is NOT
an issue if the oil is changed on the severe service schedule. Nor is
using 10W40 oil.

Not many people are aware of the Toyota problem, which I believe
was due to insufficient oil passage size to properly drain oil down
from the heads.
In that case it is obvious that more frequent oil changes would reduce
clogging of passages due to oil residue deposits, but that's no
argument for more frequent changes in general. Especially since the
coking problem was most likely caused by owners not even doing timely
"normal" frequency oil changes.
IMO, frequent oil changes are just cheap insurance against premature
wear. I'm tending more toward Steve's position lately as it becomes
evident that metallurgy and oil formulation improvements
lessen the need for frequent oil changes.
But I'm not there yet, and still use 3k miles as my measure.

--Vic