there are some of us 'men' who will choose to undergo these maintenance requirements ourselves, there are some who will never try it themselves, and then there are those of us on the fence, or in my case, who have done it BOTH ways - sometimes successful, sometimes aggravating, and yes, sometimes a lot cheaper.
I found that SpeedCo and the like can service your engine and generator quite efficiently, quickly, and with no appointment. Sure, you can arrive when 12 semis and trailers are stacked in front of you, or you might time it just right and be the only one in the whole set of bays. Their pricing may not be easy to understand, though, as even if you bring your 'own' filters, they don't typically care, and don't provide any price decrease to offset using their own brands. They may understand your RV, your DIESEL engine and generator, or they may not have had much to do with them and their 'underneath' change requirements. They may also not be familiar with the amount of oil that each needs - you best tell them ahead of time and keep a keen eye on their progress - the WILL let you watch, which is quite nice.
I would assess their pricing at about $350 for engine and generator, including all filters and oil. Speedco, though, does not do transmissions.
I've good experiences with Speedco, and a not so good one. I finally made a claim with my cc provider on the last stop, and they didn't fight it. It wound up being a 'free' oil and gen service, but at a cost. I had to relieve both the engine and the generator oil capacities as Speedco had overfilled them both...the engine should have 15qts - they put in over 23. My hitch, tow bar, tow car, and the whole backside of my rig was plastered with oil when I arrived home.
I've also changed my own oils and filters, but not my fuel filters. My engine drain pan is actually nice since it also has a side port, and the generator port is also easy to get to. The engine oil FILTER is another story, as it is WAY up and out of the way and hard to get to, much less figure out how to get any torque on it to free it up. I don't know if I want to try that again.
As for the FUEL filters - sorry, but I just can't get mine to budge, no matter what type of wrench I use - I don't want to break it in the process since it is mainly a plastic design, and FULL OF FUEL! MY secondary filter 'may' come off more easily, the one with the water drain cock, but I've not tried yet since there's no reason if the primary won't budge. I guess I'll have to leave it Speedco the next time I'm near one - though I guess the filters I bought will just be an additional cost!
Now, for the Gen - it can be a little more challenging in the tight spaces that the oil filter, fuel filter and air filter reside, but it's doable.
The 'spark arrestor' soot cleanout, though, is another challenge. If you can find it, reach it with a tool and remove it, you better WATCH OUT!, as the soot will cover you! Stay out of the way and try to have something to try to catch it. It's really just a bolt that covers a hole where this soot is contained until you can release it. I had quite a bit after 5 years and almost 600hours.
Will I do most of these things myself the next 1,500 miles or 200 gen hours?
Maybe, maybe not...it'll depend on how much of this I remember.
A clue should have been the CUMMINS dealer who had a hard time even finding what filters I actually need for this isb6.7L RV design... and then finding out that 'they' did not add the secondary fuel filter, but Freightliner did, maybe to Thor's specifications. This fuel filter they don't have, you'll have to find it on your own.
Maybe these things are simple to the garage mechanic, but to some of others it's about as clear a mud!