Smoke in engine bay after highway driving

Doh! Not good. I guess you were losing oil. Maybe the oil filter or oil pressure gauge was loose and on the highway it got too loose and you lost all the oil?

 

I honestly have no idea, I feel like I would've notice if I suddenly spilled a ton of oil on the highway... The mechanic said the leak was around the crankshaft, so I'm guessing the seal just wore out or something. Unfortunately, the fact that the engine was low on oil did not register on the dipstick, I'd been checking weekly since I bought the truck. Anyone have a clue why that might be the case?