Bulletin No. 1.62-1 Group No. 1.62 June 29, 1998 Page 1 of 2

OIL CONSUMPTION GUIDELINES

HOW MUCH OIL IS TOO MUCH?

Questions often arise regarding the amount of oil an engine uses. When the amount of oil being consumed is thought to be excessive, the concern is serious and should be addressed. Everybody accepts that an engine is going to “burn” a certain amount of oil, but how much is too much?

Although this is not always an easy question to answer, there are several guidelines which may help ease the anxiety of an owner.

Some misconceptions exist. Black smoke is a result of partially burned fuel, not oil. When incomplete combustion occurs, due to either too much fuel in the cylinder or compression gasses not expanding the rings into full contact with the cylinder walls, the result is what appears to be heavy black smoke out the exhaust. Again, partially burned fuel is the culprit. Excessive idling can cause this condition, which is commonly called “slobber” or “wet stacking”.

It the exhaust is white or light gray in color, this smoke is unburned fuel and vapor. This occurs when an engine is cold, usually at start-up in the morning.

When the exhaust smoke is blue, it’s the engine oil that’s burning. Time for real concern.

So what is normal oil consumption? Consider the following:

1. Oil change intervals should be closely followed. If extended, oil consumption will increase due to oil breakdown.

2. Check that the oil is not lost through leakage.

3. On older engines, as parts wear through normal usage and clearances become greater, oil consumption will increase relative to the degree of wear. Watch for blue smoke out the exhaust.

4. Oil consumption is relative to the amount of fuel being burned, not to time. In other words, it is proportional to the level of work being done by the engine.

Bulletin No. 1.62-1 Page 2 of 2

June 29, 1998

Over the years, manufacturers have improved the diesel engine efficiency and performance. In 1973, 25 years ago, John Deere reported that a diesel engine should average one gallon of oil to 200 gallons of fuel burned. That’s a ratio of 200 to 1. Currently, they say that a ratio of 600:1 or more is acceptable and that between 600:1 to 400:1 the customer should monitor the fuel versus oil consumed. If oil consumption below 400:1 persists after several oil changes, further review is suggested.

1. Make sure the crankcase oil fill level is accurate.

2. Inspect the air induction system for the possibility of intake of raw, unfiltered air.

3. Check compression levels of cylinders.

4. Remove head and check for glazed liners.

5. Inspect piston ring groove area for carbon build-up.

6. Inspect valve guides for excessive clearance.

So, how much is too much? Help your customers make that decision based on this information.