PLATE 6G3126 - Caterpillar

Oil Viscosity
Bearings can be damaged if the wrong engine oil viscosity is used. This is especially true in applications where there are rapid temperature changes. This is usually a problem in the spring and fall of the year. The chart that follows gives Caterpillar's recommendations for engine oil viscosity.
Many users operate with a higher viscosity oil during warmer months, intending to change to a lower viscosity oil during cold weather. This can cause problems if the ambient temperature drops sharply before an oil change is due. When this happens, cold starts are made with a heavier oil (higher viscosity) and the fluid friction is excessive. Because of excessive fluid friction, it takes longer for the oil to reach the bearings after the engine starts. Several cold starts will cause excessive wear to the engine components.
If an engine is operated with an oil viscosity too low (thin oil) at any ambient temperature, the oil film on the bearings will be too thin. Contact between the bearing and the journal can result. This will allow the bearing to wear rapidly, and can result in bearing failure. The correct viscosity to use is decided by the lowest outside temperature anticipated until the next oil change.
The use of multi-viscosity oils is preferred because they give protection through a wider temperature range.
Oil And Filter Change Period
There is no maintenance procedure as important as regular oil and filter changes. This maintenance is necessary to remove debris and chemicals from the engine. Recommendations for oil change intervals are given in the Lubrication and Maintenance Guide for each machine. The oil change interval for 651B and 657B Tractors is 125 hours. The filter change interval is 125 hours for canister type filters and 250 hours for engines equipped with spin-on filters. Sometimes customers do not understand the result of extended oil and filter change intervals. It is important to inform the customer of the engine damage that can be caused by oil that "breaks down" or filters that become plugged if the change recommendations are not followed. Remember a plugged filter permits any debris in the oil to flow directly to engine bearings and other engine components. This condition will increase bearing wear rates and decrease engine life.
Cooling System Maintenance
Lubricating oil temperatures increase as system temperatures increase. High oil temperature decreases the oil viscosity and the oil film thickness between the crankshaft journal and the bearings. If this happens the oil film can not support the load caused by combustion. This can permit bearing damage as the crankshaft journals make contact with the bearings.
Inspection and field tests of 651B and 657B Tractors show a large number operate at increased cooling system temperatures. The most common causes are radiator and air to oil transmission core passages that are closed with oil and dirt, and transmission core fins that are bent by debris.
In certain areas, sand particles can be lifted up and forced through the radiator core. This causes damage to the fins. To prevent this damage, an