Oil Consumption Test
The following diagnostic procedure is used to determine the source of excessive oil consumption.
NOTE: Oil use is normally greater during the first 16,100 km (10,000 miles) of service. As mileage increases, oil use decreases. Vehicles in normal service should get a least 16,000 km (10,000 miles) per liter. High speed driving, towing, high ambient temperature and other factors may result in greater oil use.
- Define excessive consumption, such as the number of miles driven per liter of oil used. Also determine customers's driving habits, such as sustained high speed operation, towing, extended idle and other considerations.
- Verify that the engine has no external oil leaks as described under Engine Oil Leaks.
- Verify that the engine has the correct oil level.
- Verify that the engine is not being run in an overfilled condition. Check the oil level at least five minutes after a hot shutdown with the vehicle parked on a level surface. In no case should the level be above the top of the cross-hatched area and the letter "F" in FULL. If significantly overfilled, carry out Step 5, Substeps 1 through 4.
- Carry out an oil consumption test:
- Drain engine oil and fill with one liter less than the recommended amount.
- Run the engine for three minutes (10 minutes if cold), and allow oil to drain back for at least five minutes with vehicle parked on level surface.
- Remove the oil level indicator and wipe clean. (Do not wipe with anything contaminated with silicone compounds.) Install the oil level indicator making sure to seat the oil level indicator firmly in the oil level indicator tube. Remove the oil level indicator and draw a mark on the back (unmarked) surface at the indicated oil level. (This level should be about the same as the ADD mark on the face of the oil level indicator.)
- Add one liter of oil. Start the engine and allow to idle for at least two minutes. Shut off the engine and allow the engine oil to drain back for at least five minutes. Mark the oil level dipstick, using the procedure above. (This level may range from slightly below the top of the cross-hatched area to slightly below the letter "F" in FULL.)
- Record the vehicle's mileage.
- Instruct the customer to drive the vehicle as usual and:
- heck the oil level regularly at intervals of 160 - 240 km (100 - 150 miles) .
- return to the service point when the oil level drops below the lower (ADD) mark on the oil level indicator.
- add only full liters of the same oil in an emergency. Note the mileage at which the oil is added.
- Check the oil level under the same conditions and at the same location as in Steps 3 and 4.
- Measure the distance from the oil level to the UPPER mark on the oil level indicator and record.
- Measure the distance between the two scribe marks and record.
- Divide the first measurement by the second.
- Divide the distance driven during the oil test by the result. This quantity is the approximate oil consumption rate in kilometers per liter or in mile per quart.
- If the oil consumption rate is unacceptable, go to Step 6.
- Check the positive crankcase ventilation (PCV) system. Make sure the system is not plugged.
- Check for plugged oil drain-back holes in the cylinder head and cylinder block.
- If the condition still exists after carrying out the above tests go to Step 9.
- Carry out a cylinder compression test. This can help determine the source of oil consumption such as valves, piston rings or other areas.
- Check valve guides for excessive guide clearance. Install new valve stem seals after verifying valve guide clearance.
- Worn or damaged internal engine components can cause excessive oil consumption. Small deposits of oil on the tips of the spark plugs can be a clue to internal oil consumption.