9-7X V8-5.3L (2005)
Some engines require more time than others for the oil to drain back into the crankcase. To assure a sufficient amount of oil has drained back to the
crankcase, and an accurate reading can be obtained, the vehicle should be allowed to sit for at least 15 minutes, after the engine has been shut off, before
taking an oil level reading. In order to ensure accurate results, the temperature of the oil should be close to the same temperature as the last time the oil
level was checked.
Important:
This does not apply to some Corvette ZO6 equipped with the 7.0L LS7 engine (dry sump). Follow the instructions in the Owner's Manual for
checking the oil in this application.
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 that the oil level on the dipstick is not above the full
mark or below the add marks. Refer to the Owner's Manual or Service Manual for information on recommended oil quantity, viscosity, and quality.
Aggressive Driving, High Speed or High RPM Driving
Aggressive driving and/or continuous driving at high speeds/high RPMs will 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.
A higher rate of oil consumption is normal for vehicles equipped with manual transmissions that are driven aggressively. By "aggressive," we mean
operation at high RPM (3,000 RPM to redline), with frequent use of engine braking (using the engine to slow the vehicle). Vehicles that are driven
aggressively may consume engine oil at a rate of up to 0.946 L (1 quart) every 805 km (500 mi). This is normal for a vehicle that is driven aggressively.
No repair is necessary. This characteristic does, however, require the owner to check the engine oil level at sufficiently frequent intervals, especially
when driving aggressively, to assure the oil level remains within the recommended operating range. As the Owner's Manual recommends, you should
check the oil level every time you get fuel.
Towing or Heavy Usage
Towing a trailer will increase oil consumption and may cause oil consumption 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 increases the rate of oil consumption.
Crankcase Ventilation System
Verify that the positive crankcase ventilation (PCV) system is operating properly. 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 over-full.
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 may 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.
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 0.946 liter (1 qt) in
1600 km (1000 mi).
1.
Verify that the engine has no external leaks. Repair as necessary.
2.
Verify that the engine is at normal operating temperature (see Owner's Manual or Service Manual).
