What exactly do they do for the manual transmission service? Is is basically an oil change?

 

Yes, but takes a bit longer. Sometimes if you wait in the customer lounge you get a free doughnut & coffee. There is a DIY thread on it, it you have basic tools its not hard to do.

 

Mazda dealers include their inspection. In a way you can use them to identify what else needs to be done, then check the DIY section. That's how I knew to change my brake pads. Also they offered to change my tires but went to a local mom & pop tire shop to get it done for less.

Funny at the dealer service centers they like to use their own schedules for changing tranny, coolant, etc. and discredit the owner's manual schedule.

 

Cuz they make *way more money* if they follow their own schedule.