I just bought a 2002 Argo 16 hp. Does anyone know what name this goes by?... Bigfoot possibly?

It has no gauge for hours, but it looked to be in good shape and it ran well. I changed the oil today Really? you guys go through this every time you change oil? I'd appreciate any shortcuts. I'm assuming that the previous owner didn't like the job either as the oil was filthy.

Any other things I should be doing to this unit?