Engine Lubrication: Testing and Inspection

Oil Consumption Diagnosis

An engine that has excessive oil consumption uses 0.9L (1 qt) of oil, or more, within 2,000 mi (3 200 km).
The following list indicates the conditions and corrections of excessive oil consumption:
- An improperly read oil level indicator (dipstick)
- Inspect the oil level while the car is parked on a level surface.
- Allow adequate drain-down time.
- Improper oil viscosity
- Use the recommended SAE viscosity for prevailing temperatures.
- For the proper oil viscosity specifications, please refer to Oil; Specifications, Fluids.

- Continuous high-speed driving
- Severe hauling, such as a trailer. This causes decreased oil mileage.
- A malfunctioning crankcase ventilation system
- External oil leaks
- Tighten the bolts, as needed.
- Replace the gaskets and seals, as needed.
- Worn or omitted valve guides and/or valve stem seals
- Ream the guides.
- Install oversized service valves and/or new valve stem seals.
- Broken or worn piston rings
- Improperly installed or unseated piston rings
- Improperly installed or improperly fitted piston
- Plugged cylinder head gasket oil drain holes
- Damaged intake gaskets

Oil Pressure Diagnosis and Testing

- With the vehicle on a level surface, allow adequate drain downtime (2 - 3 minutes) and measure for a low oil level.
Add the recommended grade engine oil and fill the crankcase until the oil level measures full on the oil level indicator.
- Run the engine and verify low or no oil pressure on the vehicle gauge or light.
Listen for a noisy valve train or a knocking noise.
- Inspect for the following:
- Oil diluted by moisture or unburned fuel mixtures
- Improper oil viscosity for the expected temperature
- Incorrect or malfunctioning oil pressure sender
- Incorrect or malfunctioning oil pressure gauge
- Plugged oil filter
- Malfunctioning oil bypass valve
- Remove the oil pressure sender or another engine block oil gallery plug.
- Install a oil pressure gauge and measure the engine oil pressure.
- Compare the readings to specifications.
- If the engine oil pressure is below specifications, inspect the engine for one or more of the following:
- Oil pump worn or dirty. Refer to Oil Pump Clean And inspect.
Service and Repair

- Oil pump-to-engine block bolts loose.
- Oil pump screen loose, plugged, or damaged.
- Oil pump screen O-ring seal missing or damaged.
- Malfunctioning oil pump pressure regulator valve.
- Excessive bearing clearance.
- Cracked, porous or restricted oil galleries.
- Oil gallery plugs missing or incorrectly installed.
- Broken valve lifters.