Join Date: Aug 2001
Location: Tallassee, AL
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Also, for the rear ends, those trucks with SRD, or Sterling rears, Ford states fluid good for life, as long not contaminated. For trucks with dual wheel axles, Dana types, Ford states fluid change 30k miles.
That only applies to the DRW if not filled with synthetic gear lube.
2015 Owner's Manual page 446
Change the axle fluid anytime an axle is submerged in water.
Rear axles and power take-off units with synthetic fluid and light-duty trucks equipped with Ford-design axles are lubricated for life; do not check or change fluid unless a leak is suspected, service is required or the assembly has been submerged in water. During long periods of trailer towing with outside temperatures above 70°F (21°C) and at wide-open throttle for long periods above 45 mph (72 km/h), change non-synthetic rear axle fluid every 3000 miles (4800 kilometers) or three months, whichever comes first. This interval can be waived if the axle is filled with 75W140 synthetic gear fluid meeting Ford specification WSL-M2C192-A, part number F1TZ-19580-B, or equivalent.
Add friction modifier XL-3 (EST-M2C118-A) or equivalent for complete refill of Traction-Lok rear axles. See Capacities and Specifications (page 300).
Page 304 of 2015 Owner's manual
Rear axle - F-350 (Dana 8.5 pints (4.0L) M80)
Motorcraft Rear Axle Lubricant 75W-90 Synthetic
SAE XY-75W90–QLS / WSS–M2C918–A
2015 F350 Ultra Lariat 6.7L CCLB DRW 3.73 Limited Slip, Green Gem Metallic w/ Caribou accent, Camper Package, Titan 65gal tank, Rapid Heat, Block Heater, Upfitter Switches, Dual Alternators, Camper Package, Cable Lock, Husky Floor Liners, Spray in Bedliner, 5th Wheel Prep, 25K 5th Wheel Hitch, Ford Goose Neck Hitch.
Traded 2011 F350 XLT CCLB SRW 6.2L gasser 6,000 miles for 2015
Sold 1996 F350 XLT CCLB DRW 7.3L 208,000 miles