The Rover 75 typically uses automatic Transmission Fluid (ATF) for its automatic transmission models. Specifically, it often requires Dexron III or an equivalent fluid that meets the manufacturer's specifications. For manual transmission models, a different type of gear oil is used, usually a 75W-90 grade. Always consult the owner's manual for the exact specifications for your vehicle.
If you do not want to use Polaris trans oil ,they recommend 30 w engine oil
Mopar ATF+4
90w motor oil
Use a dedicated transmission oil from Honda, either for manuals or for automatics.
Remove the transmission dipstick and read it, it will tell what is the correct fluid to use.
Dexron ATF
Dextron 2 or 3..
20-50w
Dexron 3
Use only ATF+4
SAE 75W-90
Mopar ATF+4