Puff of grey smoke when starting - Volvo 850

Light grey smoke is just water vapor, and is normal and completely harmless. If the smoke is slightly blue-tinged, it's probably just a little oil leaking down the valve guides when the car sits overnight. That isn't terrible either, but does indicate wearing valve guides or seals. It's a rare car that doesn't produce a little water vapor from the exhaust on startup. If you actually ran it out of oil, there will be problems eventually, even if just shorter engine life.

I have no idea where one would buy junk cheap oil in the USA. All of the oil I have seen forsale meets the SAE standards for modern cars. One way to have junk oil is to go beyond the suggested oil change interval.

I have owned 10 Volvos and driven them over 1,250,000 miles total and only use the oil that the Volvo manual recommends. It never recommended synthetic oil, just real oil. I have had very few problems and none engine related. When I started loosing a little oil in a '93 Volvo 850, it was because of a bad seal which the dealer fixed. An 850 should not use much oil at all. Always change oil and filter at the prescribed intervals and always check the oil level when getting gas.

There have been several service bulletins since 1993 as well as entries in the owner's manual that state,"The use of synthetic oil is highly recommended." Due to its better detergent qualities over mineral oil ot tends to keep the lifter orfices clear under extended (5000 mile or more) oil change intervals. A further benefit is that synthetic oil oxidizes less in high heat conditions which results in better lubricity and less internal heat build up from friction. This is particularly beneficial to the various lip seals in the motor.

In the OP's inquiry, the appearance of a puff of smoke on start up is usually due to worn valve stem seals. The reason the smoke doesn't persist is that the catalytic converter is scrubbing the exhaust so that the small amount of oil that is bypassing the seals is being burned cleanly. This in turn reveals where the oil is going. Since the oil volume is being reduced it tends to operate at a higher temperature and contributes less to both its cooling and lubrication function. Once the consumption increases to a quart in between 500 and 1000 miles then there is a wear issue than should be addressed. Consumption of a quart or less in a 1000 miles is considered normal.

Bob

I'm using cheap 15/40 oil which was recommended by my mechanic. They advised not to waste money on synthetic as it would consume that oil quicker due to loose valve guides or seals. I took the car on a 4000 km roundtrip about 2 weeks ago.

Han.

"Once the consumption increases to a quart in between 500 and 1000 miles then there is a wear issue than should be addressed. Consumption of a quart or less in a 1000 miles is considered normal. "

By my calculations, I'm consuming about a quart every 600 miles. You mention that the wear issue should be addressed, what can be done about it apart from replacing the engine?

The '97 850 only has 124,000 kms. If you were to make a guess, how close is the engine to giving up the ghost?

Regards,

Han.

Have someone competent look at the car and verify the source of consumption. I suspect it's a valve seal problem since that's fairly common. The engine is a sound piece and well built. Without serious abuse the motor should last well into the 200K mile range. But then it's so hard to see it from here.

Bob

Check the state of the PCV (Positive Crankcase Ventilation) system.

All the best, Peter.