Gearbox oil

Rover P4 80 I am going to change the gearbox & overdrive oil, but there seems to be a bit of confusion about which oil to use, the manuals say EP90 but some members say 20w 50 engine oil, what do members think or what have they used when doing a gearbox oil change, I also have a slight gearbox oil leak dripping from the bell housing so thinking of adding some stop leak to the refill oil so the thicker oil may be best ie - EP90


Well-Known Member
Hi, Don't bother with the stop leak additive, it works by attacking the neoprene in the oil seal making it go soft and swell up but is not a long term solution. There's most likely no neoprene oil seal to attack it more than likely a leather type seal, it's probably the clutch release gasket on the front of the gearbox inside the bellhousing.



Active Member
The stop leak might also interfere with the correct operation of the overdrive which relies on a cone clutch to transmit the drive. Also there is no conventional lip type oil seal, to swell, on gear shafts exiting into the bell housing, its a scroll . As Colin pointed out it could be the gasket or its over full with oil or less likely ,as I had on my Land Rover, the oil flinger( Shield for Primary Pinion part 01017) was missing