7G Speedshift MCT ATF Flush or just normal oil change=
2017 C218 Mercedes-AMG CLS 63 S 4-Matic with 78.000 km (48.500 miles)
I bought 12 liters of OEM MB 236.15 ATF and the full service kit (pan, filter, magnets, seals, bolts). Initially I planned to do a full cooler-line flush, but after reading more into WIS and understanding how Mercedes actually wants the 722.971 serviced, I'm starting to think the safer approach is the multi drain-and-refill method instead.
I understand the thermostat in the additional cooler is a bypass design and that oil flows regardless of temperature, but what made me hesitate is the risk of sump starvation and pump cavitation when opening the cooler circuit. Mercedes doesn't describe a cooler-line flush anywhere in WIS for this transmission, even though they explicitly allow repeated drain and refill cycles including torque converter draining.My plan now would be: TC drain + pan drain, refill and set level at 45 °C, short drive, then repeat once more. That should already replace well over 90% of the fluid without stressing the pump or clutches.
What do you guys think? Am I being overly cautious here, or does this sound like the smarter way to go on a 722.971 AMG box?
Any little detail being missed, whether its during a singular piece of maintenance or during the course of the vehicles life, and you're left dealing with an annoying aftermath.


