On Thu, 18 Jan 2007 09:07:44 -0800, SMS
wrote:

clare at snyder.on.ca wrote:

I consider about 75-80% of in-town driving (and in-region in our area)
to be "severe service".

You may consider it severe, but the manufacturer doesn't. There is no
evidence that doing twice as many oil changes as the manufacturer
recommends has any effect on engine life. It doesn't really hurt
anything to change the oil at 3000 miles, or 1000 miles for that matter,
but all the independent tests of engine wear versus oil change interval
have proved that there is no advantage to following the severe service
interval for non-severe service.


I'll agree under "normal" service - but under extreme service it DOES
make a difference - and I know extreme service.

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.
I will continue to follow and recommend the severe service schedule
for any vehicle that does not go 5000 km in 3 months, as well as any
that get high speed/heavy load use or drive the dirt roads of rural
Waterloo County.
I will also use 10W40 oil in these vehicles where 10W30 is
recommended, and in the summer wher 5W20 is recommended.
It will cost about half a mile per gallon in fuel economy, at worst.
It will NOT hurt the engine.

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