Proper viscosity selection of a lubricant is critical with all equipment components. All OEM’s will make recommendations for viscosities based on ambient and operating temperatures. These recommendations should be studied and discussed with the appropriate OEM and your lubricant supplier to assure you are using the correct product for the longest component life.

There has been a lot of discussion regarding engine oil viscosity with today’s new EPA approved engines. As in automotive gasoline engines, heavy equipment diesel engine tolerances have become tighter, and the oil is required to handle more of the load and contaminants generated by these engines.

Below are a few guidelines to consider when selecting a diesel engine oil viscosity grade:

• Ambient temperatures - Using the proper viscosity for the temperature can assist in cold starting.  The following are Cat recommendations; 0°F - 104°F use an SAE 10W30 product, 15°F - 122°F use an SAE 15W40 product
• Smaller engines prefer lighter grades such as 10W30.
• OEM manuals – Always refer to the manual for information.  As with the Cat C-9 Tier II, a viscosity plug was used above the ECM to tell the computer what grade of oil is being used.  This was the only engine with the plug and it is no longer in production.