97 ds honda clone club car cart- gear lube question

[csport]

since we have the cart working in reverse And forward, the wife asked, when was the last time, the oil, grease, stuff in the rear axle been changed?

I had to admit I haven't changed it, since I got it, a year ago and its sat right at a year-

I read either 80 or 90 weight is preferred, is there a brand of gear oil, that you prefer?

I am in the St. Louis Missouri area ( well actually 60 miles west) I am not sure if that should be considered, due to winters in central Missouri or that shouldn't matter?

thanks

any 90 weight gear oil will do
check level yearly , change every 3 years