# Carbon in the pipes

**URL:** <https://community.cartalk.com/t/carbon-in-the-pipes/80183>\
**Category:** Maintenance/Repairs\
**Tags:** cts, cadillac\
**Created:** [July 5, 2013, 11:51pm UTC](https://community.cartalk.com/t/carbon-in-the-pipes/80183 "2013-07-05T23:51:23Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![GWKA](https://avatars.discourse-cdn.com/v4/letter/g/db5fbb/32.png) [@GWKA](https://community.cartalk.com/u/GWKA)\
**Post date:** [July 5, 2013, 11:51pm UTC](https://community.cartalk.com/t/carbon-in-the-pipes/80183/1 "2013-07-05T23:51:23Z")

</div>

We have a 2008 Cadillac 3.6L direct injection CTS4 with about 53,000 miles. We bought it used and have put about 7,000 miles on it. It runs fine and I use middle grade fuel and assume the Cadillac dealership used Mobil One 5-30 synthetic oil if it was changed, (I don’t know if it was). The oil level dropped enough for me to add a qt of Mobile One recently. I read the blogs on oil consumption and it seems reasonable. However, I notice a lot of carbon in the tail exhaust extensions. I have cleaned it off with chrome cleaner but it comes back in no time. Is this a problem or a normal event for this engine series?

---

<div class="post-metadata">

**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\
**Post date:** [July 6, 2013, 12:22am UTC](https://community.cartalk.com/t/carbon-in-the-pipes/80183/2 "2013-07-06T00:22:13Z")

</div>

As long as the cars is running well and has been properly maintained, you need not worry about a bit of carbon buildup in the tailpipe. It’s normal. Keep it tuned up and serviced, monitor your fluid levels, and sleep soundly.

---

<div class="post-metadata">

**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\
**Post date:** [July 6, 2013, 12:40am UTC](https://community.cartalk.com/t/carbon-in-the-pipes/80183/3 "2013-07-06T00:40:13Z")

</div>

Probably you have emissions testing, look at the numbers. It could be burning oil or fouled injectors, bad plugs, wires etc. I would not call this normal. In fact when buying used cars I routinely check for carbon build up and pass on cars that have it. The biggest long term concern would be a catalytic converter in the future. It may go no for years, but anything building up so quicky would be a concern to me. Just for kicks I did the finger exhaust dip your finger in test on an 03 Chevy I bought 5 years and 70k mikes ago. Clear at 80k, slightest dusting of black on my finger at 147k.

---

<div class="post-metadata">

**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\
**Post date:** [July 6, 2013, 1:34am UTC](https://community.cartalk.com/t/carbon-in-the-pipes/80183/4 "2013-07-06T01:34:03Z")

</div>

I’ve noticed a lot more black tailpipes. It used to be (pre-cat converter) that you could tell if you were running not too rich by looking for light-colored tailpipes. That was probably from the lead product deposits. These days I wouldn’t worry about it, except if you are using too much oil. Keep track of it, see how many miles you go between adding a quart. You want that to be 1000 miles minimum, prefer over 2000 miles/quart.

---

<div class="post-metadata">

**Author:** ![GWKA](https://avatars.discourse-cdn.com/v4/letter/g/db5fbb/32.png) [@GWKA](https://community.cartalk.com/u/GWKA)\
**Post date:** [July 11, 2013, 1:47am UTC](https://community.cartalk.com/t/carbon-in-the-pipes/80183/5 "2013-07-11T01:47:42Z")

</div>

Thanks for the feedback. I appreciate the comments. I will watch the oil level more closely and keep cleaning out the pipes.