Mixing Coolants

What's the story with mixing different types of coolant? The other day I was on a long drive and when I stopped for gas I noticed my coolant was low. Not knowing I topped it off with the green coolant. I added about a liter.

Brought it to the dealership the next day and asked them to check it out because it seemed odd that it would be low. I explained to them that I added the green coolant because it was all the gas station had. They looked over everything and said it was all ok.

I had a coolant flush a couple months ago and they used the red/orange GM coolant. I just did some searches and people seem to say that if you mix the two coolants you will run into problems. The odd thing is the GM dealership did not mention this to me, they made it sound like it was ok that I used the green stuff to top it off.

So know I'm wondering if I should get the system flushed once again or leave it alone.

The final story is the green extended life coolants like Prestone and Peak, etc. should not be mixed with the orange Dex-cool. You may not see it initially but over a period of time you will get sludge seen mainly at the coolant reservoir tank and on the radiator cap to include radiator filler neck. So sooner or later it will need to be flushed. You can use solely the green EL coolant as long as the old Dex-cool is properly flushed out of the cooling system or keep the Dex-cool if you desire.

Prestone was pinged by a lawsuit (false advertisement) where they claimed their EL coolant can be mixed with any other coolant like Dex-cool but this has turned out not to be the case.

Thanks for the feedback, I figured it had to be done but thought I'd check.

I've been thinking about taking the advice of switching to Prestone, in order to solve the Low Coolant light issue I've been having. But now, you're saying that Prestone's claim of being able to mix their coolant is false?
They still make that claim all over their product and website. I'm now hesitant to switch to their product.

I've been thinking about taking the advice of switching to Prestone, in order to solve the Low Coolant light issue I've been having. But now, you're saying that Prestone's claim of being able to mix their coolant is false?

They still make that claim all over their product and website. I'm now hesitant to switch to their product.

Yeah, hopefully that works. :dunno: The quasi-litigation has been ongoing for a few years now but last I heard the FTC (Federal Trade Commission) is involved. Honeywell/Prestone is maintaining a recalicitrant attitude and refused to comply with a request from NAD (National Advertising Division of the Council of Better Business Bureaus). See link below.

Click here (http://www.gohtsn.com/article_321.shtml)

I see no problems with using the Prestone Extended Life 5/150 as long as the old Dex-cool is thoroughly flushed out of the cooling system before use. I converted a few years ago and use it in my GTP but not because I was having any problems with the Dex-cool.