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.

Hang on. Theres another factor here - total cost of ownership. Given
that a large proportion of "ordinary" vehicle sales are to fleets, then
its a powerful argument for Brand A over Brand B if the Brand A
service interval is 7,000miles instead of 5,000. Given that most cars
are changed over every 2-3 years (or before the warranty expires) then
it wont matter to the original owner if you change the oil AT ALL or
not - even with 50,000 miles on it.

BUT if you keep your vehicles long term, then more regular oil changes
are indeed a good idea.

Crikey - how much is 4 litres of oil and a filter anyway?.......

And for Rod to have a say - I maintain the sun will rise tomorrow - you
disagree, in your experience, of course....

Andrew VK3BFA.