Is there any problem mixing the orange antifreeze with the old green type or should I drain the old and start fresh?

Is there a preferred of these two types for the Subaru 90 Loyale?

it will work with the mix, but the orange life will only be as good as the green mixed in. but other than that it will still work like its supposed to.

 

also the orange stuff will find its way leaking through holes the green stuff wont leak thru.

 

the difference is the orange is extended life, but it doesnt do any good but cost more money if yer changin fluids every year!

 

but you can mix what you got and be good for at least as long as the green is rated for.

 

i would personally prefer the green stuff, we had an 87 spfi wagon that kept getting hot with the orange stuff, but it was leaking out of the same radiator that we had for green, which did not leak. havent tried orance since the radiator was replaced.....

I'm running my '88 on dex-cool (orange) stuff, and it's great so far. The car needed a new rad and water pump when I bought it, so after replacing those plus all my under-hood hoses (basically the entire cooling system), I figured I might as well make the switch. I flushed my system out very completely with hose water first, then soft water, and then deionized water. As long as my heater core holds up, this coolant should last until after the frame completely rusts out on this car.

 

The two coolant types are supposedly compatible, but I've heard stories about problems with some GM cars that would sludge up when the coolant types were mixed.

 

AFAIK, the biggest thing is to just make sure to use good water when mixing the antifreeze. Order of preference (best to worst): deionized water, distilled water, soft water, hard water. Hard water is better than no water, but deionized is best, if you can get it.

There are at least four broad classes of auto coolant.

 

Of these, the "American" green stuff is using a silicate base for corrosion protection, and the "American" orange (Dex-Cool compatible) is using organic acids for corrosion protection -- is that non-intuitive, or what?

 

Do not mix silicate and organic acids corrosion protection: the result is far less corrosion protection than either alone.

 

Then there is the pink stuff spec'd for Chysler, and the Zerex G02(?) for '02-on Fords (yellow), that isn't compatible with the Prestone "Gold" stuff . . . and on and on.

 

Oh, as an aside: I have a printout of an article from somewhere on the 'net here, that implies that it isn't a good idea to use organic acid based coolants in systems that are using a copper/brass radiator or heater core. Newer cars seem to all use aluminum radiators etc. so I guess that's what they mean.

 

So, no Dex-cool for our old Soobs.

 

Flushing the old stuff out every two years/30k miles is about the best thing you can do for it, regardless of what water you're using -- though I use plain old distilled water myself. If you ever do a draw test (syringe it from the radiator, put it into a glass jar), you know how crappy the stuff looks after three years, and the green stuff will be distinctly brown after two years. Brown = rust.