Owners manual

Lubricating Oil Recommendations and Specifications QSB4.5 and QSB6.7
Page V-12 Section V - Maintenance Specifications
An example of the API service symbols are shown in the
accompanying illustration. The upper half of the symbol
displays the appropriate oil categories.
The center section identifies the SAE oil viscosity grade.
As the engine oil becomes contaminated, essential oil
additives are depleted. Lubricating oils protect the engine
as long as these additives are functioning properly.
Progressive contamination of the oil between oil and filter
change intervals is normal. The amount of contamination
will vary depending on the operation of the engine,
kilometers or miles on the oil, fuel consumed, and new oil
added.
Extending oil and filter change intervals beyond the
recommendations will decrease engine life due to factors
such as corrosion, deposits, and wear.
See the oil drain chart in Section 2 to determine which oil
drain interval to use for your application.