sludge in the exhaust pipe

[jakeyseven]

i have noticed the other day , that i had black oil gundge in the tail pipe . what is this . it was not blowing oil looking smoke but there was a build up of black stuff at the backend of the exhaust

[mikered30]

It is carbon. Minimal carbon is normal but heavy deposits indicate a rich running engine or oil burning. How much oil do you burn and can you run a fuel system cleaner?

[invader]

It's carbon. Some amount of it is normal. There'll be more of it if you're burning oil and/or running rich, or have a vacuum leak which may be overcorrected and also result in combustion that is not as clean.

[johnoh]

I would check a couple other cars' tailpipes to make a comparison. Soot in the exhaust is to be expected, as is water from condensation, so they can mix and look like sludge. All cars run rich while cold, which is worse in the winter, and condensation is worse in the winter as well. Your sig shows you to be in cold/damp england, which compounds the issue. That's why I say to check some other cars to compare. The real question is do you have other symptoms such as poor mpg, a check engine code, or does the car consume oil. Don't forget to check/change your air filter and pcv valve regularly - true for all of us but sometimes neglected.