WE have been using synthetic oil in our 850 since we bought it close to
a year ago. It has a tight engine. No leaks at 120K km. WE found out
recently that it had NO block heater in it  - because it was kept in a
garage (unheated) and used synthetic oil. WE just had a block heater
installed - after all this is Manitoba and we can get occasional winter
temps at -40C.

Synthetic oil is what we use. Ursa Premium TDX that I get in 5gal (US)
pails. Costs a lot less than buying oil at Canadian Tire, and it is a
200 hour rated oil for HD use in tractor-trailers. Works fine in our
other vehicles too.

Are you saying you place the used oil from your Volvo 850 INTO your
other car(s) and continue using it as lube oil??? I seem to get that
from your sentence "in fact my used oil is in other cars who find that
they burn less using my old synthetic oil". If so, how many miles do you
keep it in those engines? If you are doing this, then why bother??  Why
not just keep it in the Volvo?

Ken
Winnipeg, Canada