I recently bought a new 2016 Porsche Cayenne V6. It developed a very bad off-idle hesitation at 11k miles, turns out it was the x-fer case slipping and the computer was trying to adjust for it. I quickly discovered that virtually every x-fer case built from 2008 has had reliability issues and the only TSB/fix so far was to install an extended case vent tube from the undercarriage to the engine bay. Supposedly this helps prevent water and dirt from getting into the case. Porsche seems to be very good about replacing the entire case without much trouble but it appears that it is either a poor design, materials, or lubrication, must likely all 3.
The design uses a wet clutch pack to vary the full-time AWD torque between front and back. BMW x-drive uses the same technology, however, they use sensors to monitor the oil and clutch pack wear and provide a warning when the oil needs to be changed.
Porsche recommends that the x-fer case oil be changed at 90k miles. Obviously this is a problem. Many owners have resorted to changing their own x-fer case oil between 5k-20k miles to be proactive. The results are shared online and the majority of the complaints are "burned oil" - that is, very dark color with a very "burnt smell".
The Porsche recommendation for the case oil is ESSO LT 71141(formerly Italian, now Mobil 1):
cSt @ 40º C 37.2
cSt @ 100ºC 7.4
Viscosity Index, ASTM D 2270 168
Density @15º C g/ml, ASTM D 4052 0.855
FP 219 deg. cel.
Many are sticking with the OEM oil and just changing it regularly. BMW oil is also ESSO LT71141 with a BMW OEM label.
I would like to find the best alternative oil to use as I believe there are much better oils now since the ESSO spec was adopted many years ago.
Since the clutch pack is "wet", the oil plays a critical role in its reliability, performance, and efficiency. The clutch is slipping by design which creates a tremendous amount of heat. Is the flash point of a viable ATF fluid a good indicator of a suitable replacement? If so, Amsoil looks to have a good product.
How about viscosity? Since the clutch is designed to slip, viscosity will heavily influence performance?
Regardless, the oil is being cooked by friction rather than contamination from moisture and dirt.
I have researched 12 different ATF oils and can not determine which specifications would suit this application. It is a transfer case, not a transmission and therefore will have completely different requirements for oil. Why would it not require something similar to a limited slip rear differential oil as it also has a slipping clutch design?
Perhaps we will require a cold weather oil and a hot weather oil?
Is there an additive that would help with the heat?
Thanks in advance!
The design uses a wet clutch pack to vary the full-time AWD torque between front and back. BMW x-drive uses the same technology, however, they use sensors to monitor the oil and clutch pack wear and provide a warning when the oil needs to be changed.
Porsche recommends that the x-fer case oil be changed at 90k miles. Obviously this is a problem. Many owners have resorted to changing their own x-fer case oil between 5k-20k miles to be proactive. The results are shared online and the majority of the complaints are "burned oil" - that is, very dark color with a very "burnt smell".
The Porsche recommendation for the case oil is ESSO LT 71141(formerly Italian, now Mobil 1):
cSt @ 40º C 37.2
cSt @ 100ºC 7.4
Viscosity Index, ASTM D 2270 168
Density @15º C g/ml, ASTM D 4052 0.855
FP 219 deg. cel.
Many are sticking with the OEM oil and just changing it regularly. BMW oil is also ESSO LT71141 with a BMW OEM label.
I would like to find the best alternative oil to use as I believe there are much better oils now since the ESSO spec was adopted many years ago.
Since the clutch pack is "wet", the oil plays a critical role in its reliability, performance, and efficiency. The clutch is slipping by design which creates a tremendous amount of heat. Is the flash point of a viable ATF fluid a good indicator of a suitable replacement? If so, Amsoil looks to have a good product.
How about viscosity? Since the clutch is designed to slip, viscosity will heavily influence performance?
Regardless, the oil is being cooked by friction rather than contamination from moisture and dirt.
I have researched 12 different ATF oils and can not determine which specifications would suit this application. It is a transfer case, not a transmission and therefore will have completely different requirements for oil. Why would it not require something similar to a limited slip rear differential oil as it also has a slipping clutch design?
Perhaps we will require a cold weather oil and a hot weather oil?
Is there an additive that would help with the heat?
Thanks in advance!
Last edited: