Why do high mileage engines burn oil?

Answer 1

easy answer ware on valve train and rings on your pistons internally or leaks around your engine externally

Answer 2

Dear Oil Consumption-

As the parts of an engine Break-In the open to larger diameters in the Pistons and Valves.

Lets do a little Automotive 101.

Frequent oil changes keep this wear to a minimum. But as with any moving metallic parts they eventually wear a pattern into the corresponding parts. This opens the specifications to a worn state. In some cases when the wear has reached a critical state then engine no longer will have enough compression to fire the cylinders.

The problem that you are experincing is called Blow By. Sometimes using oil additives, or a heavier oil can help control come of the consumption problem. But this only relates to pistons in the cylinders.

The other place that oil is pulled into the combustion chamber is through the valve stems in the cylinder head. If the stems or guides are worn you may have to have the cylinder head(s) serviced to eliminate the problem. Another problem is the valve seals. In GM products this consists of a small rubber O-Ring directly under the keeper plate on the valve. Some vehicles us an umbrella seal too. If these seals are faulty, or worn the oil that lubricates the valves is pulled down the stem and into the combustion chamber from the engine vacuum created on the intake stroke. The oils is then pulled into the combustion chamber and burned with your air/fuel mixture.

If the leakage is severe enough, this can cause oil fouling of the spark plugs, (gasoline engines), and severe smoking. On Diesel engines, this can not only create additonal smoke, but it can foul the Glow Plugs, and if severe enough, the engine may not shut down when the ingition is turned off. Yes Diesel Engines can run on their own oil too.

The repairs for oil consuming engines can be cost prohibitive. This may include boreing and hoaning the cylinders, installing new piston rings, engine bearings, and cylinder head service, to include new valve seals, guides, valves, valve seats and any additional parts to get the job completed. Basically an engine overhaul.

In some cases, if you desire to keep the car, your best bet is to purchase a replacement engine. This can be cheaper in total cost than having your engine overhauled.

But before you approach this point, try changing your oil to a heavier weight, such at 20w-50 or a selection of straight weights like SAE 30 or 40. Add a oil additive like STP and see if that helps control the oil comsumption. A product that is sold at the GM Dealerships is called EOS, (Engine Oil Suppliment). It is an excellent product.

I hope this helps you out. Good luck!

Answer 3

Some leaks into the combustion chamber past worn piston rings and valve seals from lubricated areas. You've gotten a good life out of a motor if you drove enough to start burning oil.

Answer 4

The rings are worn down. People over rev a cold engine before it has good oil pressure and the rings are dry from sitting all night.
Running a thicker oil slows down oil consumption.

Answer 5

because of wear increasing clearance between cylinder walls & piston sealing rings allowing oil to get into the combustion chamber and combustion gasses & pressure to get into the crankcase. also wear on the valve stem seals & guides allowing oil to be sucked past them & burned in the combustion chamber

Answer 6

Because the cylinders and rings are worn. So oil gets passed them and into the combustion area