KC4 is the option callout for the auxiliary engine-oil cooler — a small front-mounted heat exchanger that keeps oil temperatures in check under sustained high-load operation. On the 1987–1992 GTA platform KC4 frequently appears alongside V08 (heavy-duty cooling) when the car was ordered to specification. Cars without KC4 rely on radiator-routed oil cooling and the larger pan; for sustained track use the auxiliary cooler is the difference between a clean cooldown and warning lights.
encyclopedia · package
KC4 — Engine oil cooler
External engine-oil heat exchanger. Mandatory or near-mandatory on L98-equipped GTAs ordered with the heavy-duty cooling package.
citations
- Pontiac Firebird (third generation) — Wikipedia — Wikipedia / Wikimedia Foundation · CC BY-SA
- 1991 Pontiac Firebird Service Manual — General Motors Corporation · fair use, brief quotation
- ThirdGen.org reference threads — ThirdGen.org community · link only
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