[Bryan062087]

Long story short, someone else added NAPA brand green coolant to my truck's cooling system. Before this, I was running only the yellow Prestone pre-diluted 50-50 coolant.

A substantial amount of the NAPA stuff was added, should I worry about these 2 coolants mixing? Do I need to flush it out?

Thanks.

-Bryan

Edit: Title of thread is wrong, originally had the yellow Prestone pre-diluted Coolant.

[Tinker]

I don't think any of the normally-available coolants are incompatible. You're OK.

[2mbb]

I did a little reading. Some coolants have low silicates, others don't. If you mix too much of one with the other, you lose some of the "heavy duty" corrosion protection offered by the low silicate formulas. My guess is these coolants have been specially formulated for engines with dissimilar materials such as an iron block and aluminum heads.

I agree with Tinker that you should be OK.

[Heartworm]

Somewhere on this board I thought I saw mention to not using the Dex Cool GM type coolant with the green stuff. Maybe I dreamed it. The concern was that they did not mix together and you got pockets of one type that did not circulate as well. May be a myth, but I am good at perpetuating that.

[fliphkd778]

Taken from a respected porsche authority,
"Porsche recommends using a phosphate free anti-freeze in the aluminum engines used on 944s. Standard glycol type anti-freeze which contains phosphates will cause minerals to plate out on the heat transfer surfaces inside the engine. I've read that it isn't really isn't necessary to use phosphate free anti-freeze in the United States because most water systems have a very low mineral content. However, this doesn't take into account those who have private wells. I figure better safe than sorry. Phosphate free anti-freeze used to be a little hard to find. However, it's becoming much easier to find now days. I personally prefer Prestone Extended Life because you can buy it almost anywhere and it's not that expensive relative to other anti-freeze brands. Be suspicious of anti-freeze that says, "Safe for Aluminum Engines" on the label. Unless it specifically says "Phosphate Free" on the label, it probably isn't."

[IH8Wood]

I doubt it makes any difference in an FJ60.

[Spike Strip]

You mean the "Yellow" Preston, as Yellow bottle ? If yes, that's the same stuff

[nuclearlemon]

Originally Posted by Heartworm

Somewhere on this board I thought I saw mention to not using the Dex Cool GM type coolant with the green stuff. Maybe I dreamed it. The concern was that they did not mix together and you got pockets of one type that did not circulate as well. May be a myth, but I am good at perpetuating that.

you don't want to mix dex cool because it's an extended service antifreeze. never mix extended with old school green antifreeze. all greens can mix, but as mentioned, you may affect some anti corrosion properties. not a problem if you flush your system every so often and replace with fresh coolant.

mixing extended service and green coolants can cause bad gelling. also, many extended service coolants won't mix with other extended service coolants, so be careful there. fleetguard makes an es coolant that does mix with others, so if you need to, look for it. it will be blue in color.