Well, since the OP is talking Freightliner, we are talking about diesel pusher... which would limit the places to take it.
still doable as DIY if willing and able, but we are measuring oil to drain/fill in the 19-33 quart ranges from what I have seen.
I also expect Freightliner is doing a little more than just oil change, but is it $1500 worth?
SPEEDCO is owned by Love's Truck Stops and specialize in quick lube bays for large commercial trucks and RV's. Quick and experienced but not sure of pricing. They are located along interstates and mostly adjacent to truck stops. You can park in some of their lots overnight but noise levels are high. $1,500 seems off the chart. Sometimes people quote it high so you don't come in, but rejoice in their profits if you do.
2018 THOR Chateau 35SF
Two Labs, Bugsie & Blondie