Engine Oil Consumption Guidelines (76-60-04)

GASKET AND EXTERNAL LEAKS

Inspect oil pan and engine covers for leakage due to over tightened, damaged, or out of place gaskets. Inspect oil lines and fittings for signs of leakage.

IMPROPER READING OF THE OIL LEVEL INDICATOR (DIPSTICK)

Verify that the dipstick tube is fully seated in the block. When checking the oil level, be sure the dipstick is wiped clean before taking an oil level reading and fully depress the dipstick until the shoulder bottoms out on the dipstick tube. The dipstick should be the proper part number for the engine/vehicle that is being checked.

NOT WAITING LONG ENOUGH AFTER RUNNING ENGINE TO CHECK OIL LEVEL

The vehicle should be allowed to sit for at least 5 minutes, (15 minutes for the 3.4L LQ1), after the engine has been shut off, before taking an oil level reading to assure the oil has had enough time to drain back into the crankcase. To insure accurate results, the temperature of the oil should be close to the same temperature as the last time the oil level was checked.

IMPROPER OIL FILL AFTER AN OIL CHANGE

Following an oil change, verify that the proper amount and type of oil was put in the engine and the oil level on the dipstick is not above the full or below the add marks. Refer to the Owner's Manual or Service Manual for information on recommended oil quantity, viscosity and quality.

HIGH SPEED OR HIGH RPM DRIVING

Continuous driving at high speeds / high rpms may increase oil consumption. Because this may not always be an everyday occurrence, it is hard to determine exactly how much the oil economy will be affected.

TOWING-HEAVY USAGE

Towing a trailer will increase oil consumption and may cause it to fall below the normal accepted rate referenced in this bulletin for an unloaded vehicle in a personal use application. Large frontal area trailers will further increase the work required from the engine, especially at highway speeds, and thus increase the rate of oil consumption.

CRANKCASE VENTILATION SYSTEM

Check the Positive Crankcase Ventilation (PCV) system for proper operation. Incorrect PCV valves, blockages, restrictions or damage to the PCV system can result in increased oil use.

OIL DILUTION (FUEL AND WATER)

On vehicles that are usually driven short distances less than 8 km (5 mi), especially in colder weather, unburned fuel and condensation generated from cold engine operation may not get hot enough to evaporate out of the oil. When this occurs, the dipstick may indicate that the oil level is overfull. Subsequent driving on a trip of sufficient length to enable normal engine operating temperature for 30 minutes or more, in order to vaporize excess moisture and fuel, may give the customer the impression of excessive oil consumption.

ENGINE TEMPERATURE

If an engine is run at overheated temperatures (see Owner's Manual or Service Manual) for more than brief periods, oil will oxidize at a faster than normal rate. In addition, gaskets may distort, piston rings may stick and excessive wear could result. Verify that all cooling system components are in proper working order.

ENGINE WEAR

Piston scuffing, excessive piston to wall clearance, tapered or out of round cylinders, worn, damaged or improperly installed valve guides, seals and piston rings will all cause an increase in oil consumption.

All engines require oil to lubricate and protect the load bearing and internal moving parts from wear including cylinder walls, pistons and piston rings. When a piston moves down in its cylinder, a thin film of oil is left on the cylinder wall. During the power stroke, part of this oil layer is consumed in the combustion process. As a result, varying rates of oil consumption are accepted as normal in all engines. The accepted rate of oil consumption for engines used in vehicles referenced in this bulletin is 1 qt. (0.946 L) in 3200 km (2000 mi). This only applies to personal use vehicles maintained in accordance with the appropriate maintenance schedule,under warranty, with less than 58,000 km (36,000 mi), driven at legal speeds in an unloaded (for trucks) condition.

MEASUREMENT OF OIL CONSUMPTION

Engines require a period of time to "break in" so that moving parts are properly seated. Therefore, oil economy should not be tested until the vehicle has accumulated at least 6400 km (4000 mi). An exception would be allowed only if an engine is reported to be using more than 1 qt. (0.946 L) in 1600 km (1000 mi).

1. Check the engine for external leaks and repair as necessary.
2. Check for normal engine operating temperature (see Owner's Manual or Service Manual).
3. Make sure the vehicle is on a level surface.
4. Wait at least 5 minutes (15 minutes for the 3.4L LQ1) after the engine is shut off before checking the oil level to make sure most of the oil has had time to drain back into the crankcase.
5. Check that the oil level is at, but not above, the full mark on the dipstick and the proper viscosity and quality oil are being used as recommended in the Owner's Manual.
6. Record the vehicle mileage, date and exact oil level on the form included in this bulletin.
7. Ask the customer to check the oil level each time the vehicle is fueled following steps 1-6 and return the vehicle to the dealership if the oil level is found at or below the add mark, 1 qt (0.946 L) low. If the oil level remains above the add mark, the customer should continue to operate the vehicle and check the engine oil level until 3200 km (2000 mi) has accumulated before returning to the dealership for a final evaluation.
8. If the final evaluation shows that the engine uses more than 1 qt (0.946 L) in 3200 km (2000 mi), follow the published symptom diagnostics as described in the appropriate Service Manual. If the oil consumption test shows that the engine uses less than 1 qt (0.946 L) in 3200 km (2000 mi), explain to the customer that their engine meets the guidelines for oil consumption.

Fig 1: Oil Economy Test - Data Sheet