05 Chevy Colorado Inline 3.5L

[Jed Cooper]

My Chevy truck just turned 200k and I've always noticed a sludge buildup under the oil fill cap. It's mostly seen M1 5w30 and the HM version the last 75K miles. Is that fill cap sludge just from the oil vapors cooling? I normally do a 7.5K OCI.

 

[JavierH19]

I don't think 7.5k intervals with a decent oil will do that unless it's with around 500 running hours or more. In what amount of time does it take for you to reach that. Describe this sludge in more detail too.

 

[Jed Cooper]

Thick black paste is best I can describe. I drive about 10K miles per year. The fill cap sits high above the cams and I can't see any internals on this engine through the fill.
If that's sludge, can I expect to have some in the engine as well?

 

[oldcodger]

Check the PCV system.

 

[Jed Cooper]

PCV is built into the valve cover and has an orifice. Best I can tell it's not clogged and I generally clean the throttle body and check the valve every 50K mikes.

 

[wlk]

My vehicles do this in the winter except my wife's which she has a longer commute to work. That being said only winter, maybe try a series of 3-5k oci and see what happens. I do 5k oci now but probably going back to 3k as I have a lot of oil from clearances and even if not oil is cheap insurance.

 

[Jsm172]

My Chevy truck just turned 200k and I've always noticed a sludge buildup under the oil fill cap. It's mostly seen M1 5w30 and the HM version the last 75K miles. Is that fill cap sludge just from the oil vapors cooling? I normally do a 7.5K OCI.

Is yours burning any oil? Mine was burning oil after long trips and I finally had to take off the valve cover and clean the pcv valve. When I removed the valve cover I had so much carbon build up from the oil burning. I've been slowly trying to get rid of it through flushed and oil changes

 

[Jed Cooper]

Yes, about 1-2qts every 7.5k. But I always check the PCV orifice with a 3/32" drill bit for a gauge, and it's always clear. I'm gonna try Rotella T6 5w30 MVO with a half can of LM MOS for 2 or 3 short OCI's and see if that'll do any cleanup the M1 may be missing.
BTW my driving routine is 18mi twice each day to and from work.

 

[wlk]

Could try for a couple oci's Rislone Engine Treatment, Gumout Multi-System Tune Up or HPL EC30/40 and see if it cleans the rings up and helps reduce consumption as well

 

[Triple_Se7en]

Our donated (to grandson) 2004 Colorado 4X4 with 3.5 always gets it's oil changed at 5k with synthetic 5w30.
One quart loss at 150k is no big deal.

 

[thunderous1335]

HPL Engine Cleaner might help here