To flush or not to flush
 

I have a 96 Blazer LS. Had issues with getting the interior heating to work, and after removing a lot of gunk from plugged up parts and heater core back flushing, I am happy to say I finally have heat. I have been doing a bit of research on dex cool and have found out it is some pretty bad stuff. My question is...does anyone think it is a good idea to back flush the entire system?,or just drain the old coolant and refill with fresh Dex. I have read of issues of backflushing the system and possibly removing old garbage in the system and creating a leak. Can I replace the dex with the regular green synthetic without a complete back flush?, or should I stay with the Dex?

The problems with dex come from people not doing proper maintenance and letting it go for 5 years or 100k. You can switcch to green if you want but you have to flush out every last bit of the dex, you don't want to mix the two. Just flush each part of the system and refill with fresh dex. This is my opinion and you will likely get different ones lol.

I'm with 50lb cat on this one...

I think I will just flush out the old Dex and just replace it with some new. Thanks for your help.

I'm not a fan of dex but the 2 problems are people not changing it like they should or mixing it with normal antifreeze.


If you create a leak flushing the system that was a leak gonna happen anyways. If the system has gunk in it now do a good flush.

coolant flush
 

I just got the Blazer and I am currently going through all of it. As you stated, a major problem is leaving the dex in for too long without a flush, and mixing the dex and synthetic. I will stick to your advice and flush the old dex out and refill with new dex to avoid cross contamination. Thanks!

Dex or not, how long should the coolant be left in for before flushing (with a garden hose?)

No matter the type of coolant, a proper flush is important but you will need to use distilled water.

For mine, I think I drained and refilled from the radiator drain 5 times in order to get rid of all of the old coolant. Then I put back in 100% coolant to that the mix is 50/50.

If you can get to the block drains, then you can do a flush with garden hose and the drain it fully before refilling.