Three or four weeks ago (around the time the East Coast had some horribly cold weather) my oil consumption increased from the typical 1 quart every 1,000 miles or so, to about a quart every 100 miles, and my oil problems didn't go away with the thaw. After 8 hours parked I can see oil spots on the ground about 4" in diameter, mostly on the right hand side of the truck. When it was really cold out a couple weeks ago those spots were closer to 8". After long drives I smell burning oil, and I can see some smoke coming off the right hand catalytic converter around the O2 sensor.

I rebuilt the cylinder heads in early January which included new valve stem seals, and new valve cover gaskets. The valve cover gaskets and intake manifold gaskets definitely are not leaking. Engine compression is good so I don't think that much oil is blowing by the piston rings. The coolant isn't going anywhere and isn't contaminated. All this tends to make me think the excess oil loss is leakage rather than burning.

It's hard to pinpoint where the oil leaks from - it seems like it's getting blown all over the place on the highway. I took some pictures to show what's going on.

• Oil pools in the casting pockets on the top side of the front differential.
• Behind the oil filter, nearly every surface is covered in oil - especially the split loom tubing running rearwards past the starter motor.
• There is also a little bit of oil on the left side of the engine, but in far lower quantities.

Right now I'm beginning to think the leak is coming from the front crankshaft oil seal. Does anyone have any ideas?


Lower leak area

Upper leak area

 

I would check the oil cooler lines and double check the oil filter is seated correctly.

 

Oil Cooler line condition looks questionable (those appear OEM), oil cooler line connections on the front timing cover 7/8 wrench fits them, front main seal are where I'd start.

 

One other thing to check is the oil filter gasket. The gasket on the oil filter will sometimes separate from the filter body and get stuck on the filter housing. Double gaskets will cause a major leak.

 

The usual suspects are

Crank seal - replace with speedy sleeve l
Various oil lines - replace where needed
Oil filter - lose or gasket
Leaking oil plug and crush washer
Oil pressure switch - replace (this will cause oil pressure light to come on so that is easy to tell)

Degrease the bottom of the engine and put a large piece of cardboard under to help you see where leak area is to narrow it down

 

Thank you all for the input, here's my work list for anyone who comes across this post in the future. I'll reply back with a conclusion in a week or two.

• Replace main seal.
• Replace front cover gasket.
• Replace timing chain and sprockets (while I'm in there).
• Replace oil pump "gear" (while I'm in there).
• Re-seal oil pan (the timing aligns with my oil pan heater installation).
• Replace upper and lower oil cooler lines.
• Remove and inspect oil filter for double seal.
• Replace oil pressure switch.

 

Common causes include worn piston rings, valve seals, or a failing PCV (positive crankcase ventilation) valve, which can lead to excessive oil consumption. If you notice blue smoke from the exhaust, your engine is likely burning oil.