That 30w oil has done the job since 1969. Very low forces are on those gears in that transaxle. I put non detergent 40 weight in an old 1980 garden tractor 20 years ago which is what was called for, I haven't changed it since and it is still going just fine with a lot of use. We are not talking hypoid gears here. I don't think it is that critical what is in that transaxle, it is not going to self destruct.
Originally Posted by MolaKule
So no transaxle gear boxes ever need Anti-Wear additives?
Originally Posted by mker
I would just stick with non-detergent 30 weigh oil. I am pretty sure back in 1969 there were already all sort of gear oil available yet it didn't ask for it back then. You can never be sure there no copper components inside the gear box. Why take a chance with something else?