Transfer case sight glass & filler bung
The factory oil is mineral based and rated at 90deg, the transfer case will see temps of around 100deg on highway driving.
We upgrade the oil to a semi synthetic type of oil at the same viscosity which has a higher temperature rating.
We change the plastic sight glass to a brass type with glass window and replace the plastic fill bolt with a brass type due to seeing failures after a period of time.
This allows the service schedule to be put in line with the engine oil change schedule.
FITS: 55S17W, 55-180 (Part # TT07.08)