Today i changed my oil....switched oils about 12k ago to valvo blue 15w-40. Everything runs good. I went 6k on this run..I had to add about a quart at 3.5k...not to bad...about the usual. When I was pouring my old oil back in the jugs it only took about 2 gallons (8 quarts) just about to empty my drain pan. I understand the filter takes some. Oil gauge is in normal range. Oil level on the dipstick is in operating range. My truck doesnt have an oil leak, never has, I check my oil reguarly. Do diesels usually drink this much or is mine just special like that..?