A Tip from Bob Agnew . on gear oil on your AMPS lowers Ken passed this on to me to answer

In the days when the AMPS products were originally produced there were not as many good oils on the market as today.
You can use any good quality Hypoid Oil (Automotive gearbox/Diff).

The thing to remember is not to over fill the gear casing and in the case of the outdrive to keep an eye on the top gearbox. When the drive runs it pressurises the oil in the gearbox so if you do overfill it do not worry if oil seeps out of the bearings.

The other problem if you overfill the lower unit is that the oil can get very hot so if the boat stops out on the water then ask the oil cools it can suck in a small amount of water.
If you fill the gearbox about half full that is a good guide.

Regards

Bob Agnew