A cooler that weeps at the core, an oil temperature that climbs under load or coolant contamination in the transmission fluid all point to this group.
On many engines the oil cooler sits in the valley under the intake and mixes oil and coolant when its gaskets fail, which produces the milkshake that destroys bearings. Coolers are matched to the engine and to the transmission it serves, and a universal cooler of the same physical size may have a different internal volume that changes warm-up behaviour.
Listings state the cooler type, the connection size and the engine codes covered. If you find oil in the coolant or coolant in the oil, pressure-test the cooler before replacing the head gaskets.
