The 68RFE is the 6-speed automatic behind the Cummins diesel in the RAM 2500 and 3500 from 2007 onward. It's also one of the most hotly debated transmissions in the diesel truck community — and for good reason. It has real weaknesses that Chrysler never fully addressed, and understanding them is the difference between a truck that tows reliably for 200,000 miles and one that's rebuilt twice before 150,000. The known weak spot is the overdrive clutch pack and the transmission's overall clutch capacity relative to the torque loads it sees behind a high-output Cummins. The stock 68RFE was engineered for the factory Cummins tune — around 350 lb-ft of torque at the crank. Many RAM owners run aftermarket tunes that push that figure significantly higher, and the 68RFE's clutch pack capacity simply was not designed for sustained operation at those torque levels. Even on a stock tune with heavy towing, the 68RFE runs hot and the overdrive clutch pack is the first casualty.
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Mopar ATF+4
Search AmazonThe only fluid spec for the 68RFE. Mopar ATF+4 is required — substituting Dexron or generic ATF changes the friction chemistry the overdrive clutch pack depends on and accelerates the exact failure mode described above. Pick up 6–7 quarts for a drain-and-fill service. Service every 30,000 miles under towing duty.
Check Price on AmazonBlueDriver Bluetooth OBD2 Scanner
$89.95Reads Chrysler-enhanced transmission codes including P0734 and P0735 — the early 68RFE overdrive clutch slip indicators. Monitor live TFT during towing to know when your transmission is running hot. Catching P0734 as a pending code before it goes hard is the difference between a fluid service and a rebuild conversation.
Check Price on AmazonLucas Oil Transmission Fix
$14.87For 68RFE trucks showing early overdrive slip with otherwise serviceable ATF+4, Lucas Trans Fix added to a fresh fluid service helps recondition clutch surfaces and improve hydraulic film strength in the valve body. Use alongside — not instead of — a proper ATF+4 drain-and-fill when early slip codes appear.
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