My new-to-us (and our first Volvo) 740 Turbo has been smoking at the exhaust pipe when the engine's cold. I took the car to our local Volvo specialist, who said the smoke was caused by oil. He drove the car and said it seemed fine, but noticed some uncharacteristic "piston-knock." His opinion is that the oil could be coming from either the valve guides, bored out cylinders, or oil in the intercooler (It's a new Turbo in a car w/ 86,000 miles). He said that, as long as I check the oil regularly and keep the level where it should be, there's no reason to think that the car won't live a normal life. Sound reasonable? Any suggestions? Thanks!