There is TONS of information out there on the different types of coolant.
Here's the Cliff notes:
First and foremost, any type of coolant can be whatever color the MFG decides to color it, so do not go by color, only go by type.
There are three basic types of modern coolant, and they all contain an ethylene glycol base, water, dye and an additive package. Each type is referred to by the additive package it contains:
- Inorganic Acid Technology (IAT)
- Organic Acid Technology (OAT, also known as Dex-Cool)
- Hybrid Organic Acid Technology (HOAT, also known as formula G O-5)
IAT is almost always green, and is what most people would associate with "regular" coolant. It gets its name from the inorganic rust inhibitor package it contains, and has a rather high silicate content. The nature of this package causes it to break down as it performs its job of prohibiting rust, and as it is exposed to air and heat/cool cycles. This is why the coolant needs to be replaced so often. There are no longer any vehicle MFGs that use this coolant in their vehicles.
OAT on the other hand, contains no silicates, and inhibits rust using a purely organic package. OAT coolant is most widely used in the US by GM, and different formulations are used by many MFGs in Europe and Japan. This type of coolant is most often found in "closed" coolant systems where the entire system, including the overflow, is pressurized.
HOAT, as you may have guessed, is similar to OAT, except for that it also has silicates in it. This is seen by many as the best of both worlds, and Chrysler, Ford, Mercedes and BMW (among others) tend to agree. This type of coolant is most often used in "open" coolant systems that have non-pressurized overflows.
Here's where the arguments arise. Can you mix the different types? IAT and OAT cannot be mixed. Their rust inhibiting packages are just too different, and in some cases react to each other. Don't do it. HOAT can be added to either of the others with these caveats: 1) adding HOAT to IAT does not lengthen the service life of the IAT. You should still change it at the recommended IAT intervals. 2) Adding OAT to an "open" HOAT system has been known to cause build-up issues in the radiator and passages of some
vehicles. Your best bet if you want to use a different type, is to completely flush the old type of coolant out before pouring the new in, as this rarely causes issues.
In conclusion, is there a "universal" coolant that can be added to any "color" that is already in your system? Absolutely not, and many coolant MFGs are being sued over such claims. You cannot
have a coolant that meets both
the silicate specs of IAT and the non-silicate specs of OAT at the same time. It cannot be done. As NV290 said, when it comes to any Chrysler vehicle from '02+, there is no reason not to use HOAT coolant. Valvoline Zerex G-05 is very popular, and the Chrysler MS-9769 is not much more expensive and available at pretty much any dealership. I changed mine a few days ago at around 60k, and it came out as clean and clear as the new stuff that went in.