Six quarts of Mobile 1 5W20 full synthetic oil and 1 Motorcraft FL820S oil filter at local Walmart is $39.55 out the door. Oil analysis from Blackstone to include a Total Base Number (TAN) of remaining additives is $38.00. If I go with just conventional oil rather than synthetic I could get the cost under $30. I could maybe get the cost almost under $20 using generic or store brand oil and filter.
For a gas coach, if an owner is not capable of changing the oil AND the engine warranty has expired so they can go beyond the recommended interval (time or distance) without the concern of warranty volition then drawing a sample and having it checked could be a potential a cost savings. Even more so for the transmission which is much more expensive to have performed and a high cost for materials.