CORE AS-RADIATOR 2139907 - Caterpillar

no longer recommends the use of multigrade oils containing viscosity index improvers in powershift transmissions. SAE 10W30 and 15W40 are the two primary viscosity grades that are affected. Special synthetic oils that overlap more than one viscosity grade without the use of viscosity index improvers are still acceptable for low ambient temperatures. Certain single viscosity oils contain viscosity index improvers to reduce engine oil consumption. If one of these products is considered for use in powershift transmissions, the base oil viscosity must meet the SAE J300 specification for the SAE viscosity grade marketed.
For the performance requirements of the transmission, use Caterpillar Transmission/Drive Train Oil (TDTO) or commercial oils which meet API CD/TO-2 and/or military specification MIL-L-2104D.
In April of 1982, Caterpillar published recommendations concerning the ambient temperature limits for different viscosity grades relative to SAE J300 SEPT 80 classification. This publication included the use of multigrade oils (10W30 and 15W40) in powershift transmissions. The use of multigrade oils was limited to the base oil viscosity; for example, SAE 10W30 usage was restricted to the same ambient temperature limits as an SAE 10W oil. This restriction was due to heavily-loaded gears and rolling element bearings that do not derive the benefits of the viscosity index improver that makes an SAE 10W oil act like an SAE 30 oil at high temperature. However, these restrictions have not been observed. Multigrade oils have been used across the full range of their implied viscosity range. (A 10W30 oil is used in place of both and SAE 10W and an SAE 30). Because of transmission problems associated with the misapplication of the multigrade oils, they are no longer recommended for Caterpillar powershift transmissions, even though some earlier-published information included them.