I have a 1993 940 with 143,000 Mi. I recently had an oil change at the local franchise of a big chain oil and lube place (not sure if mentioning the shop name here jeopardizes this message board in any way). They strongly suggested an engine flush using their machine - I declined, discounting it as sales pressure. Is an engine flush usefull, and when is it called for?
Also, should I consider switching to a synthetic motor oil? I've known this car's life history and it has always been maintained with stanadard motor oil. Does switching now make sense? I want to take the car to at least 200K mi in the next three years.