Transmission auxiliary oil cooler ($15.80 in 1969, for trailer towing)

Years 1968–70 Models 3 Factory citations 1

Also described as Auxiliary oil cooler, automatic transmissionAuxiliary oil cooler — automatic transmission (trailer hauling)

Documented applications

Cutlass / 4-4-2

1969 Factory-verified

Factory optional-equipment list: "Auxiliary Oil Cooler, Automatic Transmission"

GM Heritage factory kit — 1969 Oldsmobile 442 Info Kit, p.247.

Full-Size 88 / 98

1970 Confirmed

—

Grade note: confirmed [HK: oldsmobile/1970_Oldsmobile_442_Info_Kit.txt p.236]

Toronado

1968–70 Confirmed

—

Grade note: confirmed [HK: oldsmobile/1969_Oldsmobile_442_Info_Kit.txt p.140]

This page aggregates every documented appearance of M-55 in the Oldsmobile reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.