# Flushing dexcool sludge

**URL:** <https://community.cartalk.com/t/flushing-dexcool-sludge/46547>\
**Category:** Maintenance/Repairs\
**Tags:** silhouette, oldsmobile\
**Created:** [March 24, 2010, 12:51am UTC](https://community.cartalk.com/t/flushing-dexcool-sludge/46547 "2010-03-24T00:51:45Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Frank\_B](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@Frank\_B](https://community.cartalk.com/u/Frank_B)\
**Post date:** [March 24, 2010, 12:51am UTC](https://community.cartalk.com/t/flushing-dexcool-sludge/46547/1 "2010-03-24T00:51:45Z")

</div>

I need to flush out the cooling system on my wifes 2003 olds Silhouette. It looks like I am facing both issues of old dexcool sludge/mud, and the effects of green antifreeze being added at some point. We bought it used so I have no idea of the history.  
  
 Anyway, I’ve tried the off the shelf flush from the parts store and it didn’t cut it. has anyone found a product to cut that sludge??  
  
  
  
 Thanks

---

<div class="post-metadata">

**Author:** ![waterboy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/waterboy/32/764_2.png) [@waterboy](https://community.cartalk.com/u/waterboy)\
**Post date:** [March 24, 2010, 1:12am UTC](https://community.cartalk.com/t/flushing-dexcool-sludge/46547/2 "2010-03-24T01:12:05Z")

</div>

You need to flush the system entirely then use something like peak global as a replacement. Sludge with dexcool is many times associated with air being introduced into the system, so you should check pressure and any coolant loss sources also.

---

<div class="post-metadata">

**Author:** ![Frank\_B](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@Frank\_B](https://community.cartalk.com/u/Frank_B)\
**Post date:** [March 24, 2010, 1:20am UTC](https://community.cartalk.com/t/flushing-dexcool-sludge/46547/3 "2010-03-24T01:20:44Z")

</div>

Thanks, I did flush the coolant, but the system is coated with the brown gunk.

---

<div class="post-metadata">

**Author:** ![oldschool](https://avatars.discourse-cdn.com/v4/letter/o/e19adc/32.png) [@oldschool](https://community.cartalk.com/u/oldschool)\
**Post date:** [March 24, 2010, 2:32am UTC](https://community.cartalk.com/t/flushing-dexcool-sludge/46547/4 "2010-03-24T02:32:58Z")

</div>

GM itself has a flush procedure for dexcool sludge, do a general Service Bulletin check for the product GM recommends.Dont expect the overflow bottle to come clean and the heater core may not come around, what area is giving trouble?