Cummins has recommended against factory fills of extended-life coolants in its engines until a solution to a seal problem can be found.

These coolants, which have a special organic acid chemistry that allows them to run longer in engines, are apparently causing degradation of silicone seals in Cummins engines after 80,000 to 100,000 miles of operation.
The extended-life coolants are made by Equilon, a joint venture between Texaco and Shell. First introduced in 1994, they are sold with slight variations in formulation under various brand names, including Texaco Extended Life Coolant, Cat Extended Life Coolant, Shell Rotella Extended Life Coolant, and Detroit Diesel Power Cool Plus.
In a joint consumer bulletin issued Friday, Cummins and Equilon said that adding silicates to ELCs or installing a coolant filter containing silicates can help slow the seal degradation. Initially Cummins recommended draining the coolant and replacing it with conventional coolant, but the company now says that "may not be necessary or helpful" because it will not remedy the situation.
Equilon is considering a program to offer silicate additives free of charge to Cummins owners using ELCs. It is also working with various filter manufacturers to come up with a recommendation for a filter. But both companies caution that over-treatment of silicates can lead to damage of other engine components.
It has not been determined who is responsible for engine damage and repair costs caused by the leaking seals. Equilon and Cummins are working on a permanent solution.
Other engine manufacturers are standing behind extended-life coolants and recommend continued use. But Caterpillar and other engine makers say truck owners should be careful to use the right replacement seals when repairing engines. Some may not be compatible with these coolants.