Oil in Muffler!

Was having a cage installed on the heap, and figured while it was in the shop I'd replace the glasspack with something quieter for the long road-trips.

When they took the glasspack off, they called me and said that I have oil in my old muffler!

When I drive it, I have NO smoke of any color, from the exhaust or anywhere else. I do SMELL oil burning, but there is no smoke, so I just assumed it was a drip onto the exhaust somewhere. Shop's thinking was that the oil in the muffler is blowby past the piston rings, but I have NOTHING indicating loose rings or cylinders; no knocking/slapping, no low oil pressure, and I am not burning through oil, etc. I even asked if it was OIL they found or just water/soot. They were sure it was oil.

It's an XJ, 2001, with 190K on it, original 4.0IL V6. Has plenty of power and acceleration, even rolling 35's on 4.56.

Anyone seen/heard of this before? Any solid thoughts on what it ACTUALLY is? I've seen/heard rings, valve seals, and valve stem guides, but ALL seem to be indicated by SMOKE, which I don't have.

Assuming it is the piston rings, if I keep oil in it, can I just keep driving it, or am I likely to throw a rod?

Do you have a cat? If yes I would bet it would burn the oil up before it gets to the muffler. I would bet its soot mixed with condensation.

shop is full of shit, if it was piston rings it would smoke at higher rpm's, my 95 does that and I have no oil in my exhaust

blubullett said:

Do you have a cat? If yes I would bet it would burn the oil up before it gets to the muffler. I would bet its soot mixed with condensation.

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I do have a cat, 2 in fact! (I have 2001, which came standard with CA Emissions on all of them, so I have one mounted on the side of the engine, and then the P.O. installed another one inline when he installed the glasspack)

ROBZ95Xj said:

shop is full of shit, if it was piston rings it would smoke at higher rpm's, my 95 does that and I have no oil in my exhaust

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That's what I thought, too! I run this thing up to about 5000-5500 rpm accelerating onto the freeway and nothing! No plume out the back! (I used to have a VW Beetle with loose rings (what VW bug DIDN'T have loose rings) and I use to lay down a mean smoke screen when I accelerated.

The oil may have been in the muffler before it was originally installed. This would account for the smell, but no smoke. Machine oil is often used during the manufacturing process, and may not have been properly cleaned up before you bought it.

Moisture, soot and rust may have accumulated as well, making it appear to be engine oil.

Some engine can use a quart every 500 miles and there's no smoke to be seen. Do you have to add oil to the engine frequently?

At least the muffler wont rust out.

Jesse_Hallum said:

The oil may have been in the muffler before it was originally installed......

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This would be my guess too. It's probably packing oil
that settled out of the muffler and collected on the bottom.
Since the shop didn't say how much oil they found, it
might have been only a few ounces...????
Nothing to worry about.

It's muffler fluid. It's to keep the muffler bearings from drying out and seizing.

If you had oil in your muffler, I'm betting your cats would get plugged first. You would also be consuming a TON of oil. I agree that it is condensation mixed with soot from the exhaust.

I wonder if this shop rebuilds engines and is eager to sell you a new engine?

I rolled my rig onto its lid and it sat for a while upside down. the exhaust, along with the intake and cylinder head where full of oil. Like tons of it.

Duh! The oil is for the muffler bearings!

https://www.youtube.com/watch?v=NQspesBGpBg

It would be easy to eliminate the engine as the cause by doing a leak down test.

I ended up compression testing the valves. The lowest I got was 135 (the rest were 145-155). When I put a little oil in to see if the ring was loose, I got the same compression level. Then when I started it up, the damn thing blew a smokescreen for about 10 minutes!

I was down a couple quarts (got a leaking oil pan gasket I need to change) so I topped it up, then drove it 600 miles to CO and back over Thanksgiving. Haven't lost any oil. The thing ran fine.

I'm going with carbon/water mixture on this one. Nothing else seems to say there is oil getting in there.

Thanks for all the help and suggestions!