I have always used gas powered trucks and SUV's to tow and the heaviest tow was a 12 horse trailer. My 2011 diesel needs very little attention and as it is used for "severe duty" 50% of the time I have adjusted the oil changes to 7500 mile intervals. It is 10 quarts plus $10 for the filter. I don't use synthetic for several reasons, it provides no benefits at temperatures greater than zero degrees and at normal and high temperatures a 5W-40 provides poorer lubrication than a 15W-40 oil both due to the presence of temporary polymer shear and the greater problems with any particulates.
Companies are starting to put 15W-40 synthetics on the market but with the 7500 mile change interval it would still provide no benefits. I want to change the oil to remove any possible soot and sludge at 7500 mile intervals regardless.
The Allison transmission requires more maintenance in terms of lubricant and filter changes but that is a good thing as it will help to maximize its life under severe duty conditions.
Much of the more frequent maintenance and lubricant changes would be required with a gas powered vehicle if subjected to the same type of use. If a vehicle was used 90% of the time for around town driving then a gas engine would be a better choice as diesels do not do well with lots of short trips where the engine does not come up to full operating temp.
A diesel is in some ways a luxury item but then so is a heavy recreational trailer - it goes with the territory.
