Andrew VK3BFA wrote
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,

Wrong.

then its a powerful argument for Brand A over Brand B if
the Brand A service interval is 7,000miles instead of 5,000.

Wrong, and you say why its wrong in the next sentence.

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.

Great footshot.

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

Yes, but you havent established that the
lower rate will see any long term problem.

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

Quite a bit if you double the frequency and pay someone to do it.

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

You'll end up completely blind if you dont watch out, bludger.