So uh, F350DRW1, 15qts. is a quart shy of 4 gallons. . . just in case you ever poured in a full 4 gallons and had some problems.
No, I haven't. There was an entry early on in this thread [that has since been deleted] that mentioned 16 quarts. I'm not the sharpest knife in the drawer, but thats pretty close to 4 gallons. So my reply is now out of context.