Motors in theory shouldn't consume oil, oil is not consumable in any way by the engine, it is a lubricant for the moving component in the engine... with that being said, your oil can seep out or leak out of the engine, otherwise is being passed through the piston rings into the combustion camber and burned off, but if this is the case you should also be experiencing some degree of excessive blow-by as diesel engine do generate more blow-by than gas engines as it is... get it checked out, you should have zero oil losses between 5000 miles intervals...
I bought the truck in December with 3400 miles. It's a 22 F350 Tremor. It's completely stock and was very lightly used by the original owner only to commute to and from work. The oil had been changed just before I bought it. At 4500 miles I changed oil myself because it wanted to use Rotella T6, that was a few weeks ago and the dipstick read full when I finished (top of bracketed range). Last week we took a trip that included considerable mountain elevation changes so for the first time I used the engine brake for decent assistance for probably a total of 200 hundred miles. Prior to changing the oil I hadn't noticed any changes to the dipstick reading during the 1100 miles from purchase to my first change. After washing the truck today I checked the oil level and it was low, took about 3/4 quart to get back to the previous level. I'm not seeing any leaks. Oil looks normal.
Just to confirm after you were "done" doing the oil change, I supposed you started the vehicle and check for leaks which there was none and then you turned the truck off, did you double check the oil again after doing that, the reason I'm asking is because some of the oil that you put in, now houses itself in the oil filter, so after an oil change and first start up oil goes to the filter and only after that you top off your oil once again, if you didn't do that, makes sense you will see a difference in oil about "1/2 or 3/4" of a quart should be expected with such a big oil filter... now that you explained what had happened before your findings of oil difference, it kinda make sense... I think if what I explained in this post is what happened you'll be alright bud just top off your oil and go on your happy way...
After completing the oil change (and numerous start ups and leak checks) the dipstick was on location "B". Upon returning from my trip it was on location "A" and it took about 3/4 quart to get it back to location B. Although I haven't crawled under the truck since returning there are no oil drips where I park in the garage. Nor where I washed the truck yesterday. Tail pipes are clean inside and show no signs of oil residue. Like I mentioned, I don't think I saw any oil consumption before this trip where I've now used the engine break for an extended period and after changing to Rotella T6. Guess I'll have to get it back on the road and see if it continues this trend. Does anyone know if using the engine break could be responsible for this? The only other oddity was my DEF gauge was reading 4000 miles before the left to now its reading 2500 miles. My total travel was no more than 1000 miles.
