model 3012x6s mower. motor is b&s 12 hp. someone said it is a '86 manufacture
I cannot find a motor s/n or model # , It is white I-tec.
I don't know what difference the engine makes for transmission fluid.
someone posted on a different thread that they used 00 grease in the transmission and differential case
See my post on "my (new to me) snapper rider below
00 grease is correct. It shouldn't be much trouble to find. Sten's carries it and I'm sure other parts places do as well. Series 6 mowers were the last ones before the "square tube" mowers, which I believe came out in '89 or '90. Yours was probably made in '87 or '88.