Trying to figure out a true cost to run a piece of equipment is fairly complex, depending on what all you want to consider operating costs or repair costs. A machine with only a couple expensive breakdowns will look worse on paper than a machine with a lot of small, inexpensive repairs, but if you take into account the cost of downtime, the machine with the cheaper repairs might actually be worse. No time can you include accidents or operator error breaks into the repair costs when comparing machines, that's not a fair comparison. Consumables should be added into the repair costs as some brands will cost more in some departments than others. Regular maintanence should be included also because if you think you are saving money on filters and oils, it will show up in the actual repairs! To some degree, operating costs like fuel can be included in the overall comparisons. For example, our CX we have uses between half to 2/3's the fuel our CR's used, so if we end up putting more money into the CX for parts than we did for our CR's, it will still likely be a cheaper overall machine to own and operate. It's a fairly grey area when trying to compare one machine to another. Every farm will do it a different way, and doing it by acres/hours/bushels is up to you as long as you do it the same for all machines.