As long as you keep your receipts from doing it yourself I think you'd be ok.

 

Just change it yourself keep you recept's for everything you buy fluid's and any maint items. We recomend 15k for diffs service. but there is nothing that says you cant do your own work. Maybe you tow a boat and backed in the water to launch it maybe to far. Who knows? when your in the shop about all we can tell you about your rear end is it's full and what the fluid looks like untill we remove the cover.Would you not want to know what the gears look like and whats in the bottom of the case? Removing the cover is the main part dont go to place that will only suck it out. quick lube places like to do it that way