I know that Tom and Ray have said in the past that you can mix coolants, but I have been on a forum that had an individual make the following statement about coolant:

Tom and Ray usually know what they are talking about, but this time they made a mistake. There are basically THREE types of coolant. One, “OAT” has “organic” additives, “IAT” has inorganice, and “HOAT” has a “hybrid oraganic additive technology”. IAT is the classic Prestone and is usually green. The inorganic is silicate, and it protects metal surfaces from corrosion. But some manufacturers wanted something better for engines with a lot of aluminum, so they developed “OAT”, which didn’t work very good when it first came out in the 1980s. Now it is all better. But because silicates work so well, some cars use the hybrid, which has just a little silicate, and also the organic additives. It used to be easy, because European cars used one, American cars used another, and Japanese cars used the third. (Mercedes and BMW use blue coolant sometimes) But now it’s hard to identify which one to use, and the manufacturers sure don’t help by putting all the info on the label. Sure would be nice if every owners manual came with a list of approved products. Or maybe they could post it on line, so it would be easy to update.

I am just wondering if this is true…and if so, should you purchase only the OEM coolant, or is it okay to use the old standard “prest___” type?

If your car uses the good-old green anti-freeze, you can mix it with any other green anti-freeze. It’s not a good idea to mix different colors, or types, of coolant together. Some combinations will gel, and gel does not make a very good engine coolant.

In other words, the TYPE of coolant matters, but as long as you use the correct type, brand does not matter.

What color is the coolant in your car?

Standard may not be standard anymore. I use the Zerex chart recommendations exclusively, to avoid confusion on my part.

That said, Dexcool or any of its clones should not be mixed with anything else. Several manufacturers now claim that you should use OEM because their mix isn’t exactly the same as the after market, even though testing may indicate otherwise. Universal is supposed to be universal, but there have been instances where mixing doesn’t work well. Some claim universal to be a dex-clone, and several people would never, ever use Dexcool again in their lifetimes.

See Coolant topic for even more confusing info than what I provided here. You didn’t tell us what car you have, but my short answer would be that you don’t necessarily need to use OEM coolant, but you need to be careful about what you do use and make sure it meets the specs for your particular car.

I go with Zerex as well. You can get all their flavors at NAPA.

Use whatever your manufacturer recommends, unless of course the manufacturer is GM. If your system calls for Dexcool, get a good flush and use old fashioned green instead. My dislike of Dexcool comes from much personal experience with it. For any other manufacturer use OEM coolant. Yeah OEM at the dealer costs a little more, but as infrequently as coolant needs to be refreshed, a few dollars isn’t a big deal here.