[duncan1437]

i purchased a low mileage 1989 reliant (2.2 liter) in the spring (about 40,000 miles/60,000 kilometers). i'm going to change the coolant, but the original owners&shop manuals seem quite out-of-date with coolant developments over the last 20 years.

i spent a day reading up on the topic and frankly i'm a bit overwhelmed at all the different chemical additive packages (silicates, silicate inhibitors, phosphates, 2-EHA, dexcool, OAT, HOAT, etc), and which to choose.

the coolant currently in the car is green. what coolant would you choose?

i have already purchased some 'prestone long life concentrate' (all makes, can mix with any color) but i can return it if necessary. the ingredients are ethylene glycol, diethylene glycol, sodium 2-ethyl hexanoate and sodium neodecanoate.

i've learned alot about drilling a hole in the thermostat, putting the car on an incline and burping the radiator, flushing the system to avoid mixing incompatible chemicals, etc, but i havent been able to decide on which coolant to use. :frusty:

any comments/experience would be appreciated. thanks

 

[RRToadHall]

Drain it, flush it clear and pickup whatever is on sale. I stayed with the appropriate green standard for my 84 with 45K. It is usually the cheapest, readily available and is the same across msot of my cars save for my 300.

I am intrigued by your comment of drilling a hole in your thermo. My temp fluctuates occasionally. I have gone through three thermos, two different brands. Two total flushes. Radiator fins are clear, fan works appropriately and interior of the radiator has very little signs of any corrosion. It;s not perfect, but very close to it.

 

[VillageIdiot]

Good ol' green is what I would use. If you do drill a hole in your thermostat (to help bleed any trapped air), a 1/16th or 1/8th hole is good, make sure the hole is in the 12 o'clock position when you reinstall the thermostat. Point the front end of the car uphill, remove the radiator cap and run the engine until the thermostat opens. The coolant level will drop when the thermostat opens and any trapped air should be purged out. Put the cap back on (engine on or off, doesn't matter), top up the overflow bottle and you're all set.

 

[Bob Lincoln]

I'd just use the green Prestone 50/50 pre-mix in that vintage car. That way you know the temperature protection is correct, and it's compatible with the engine and cooling system.

The hole in the thermostat is unnecessary. Just burp the cooling system by parking uphill and running it with the cap off until the air is purged. Never had an issue in 27 years of owning these cars, and over 500,000 miles. If you still have a problem with air in the system, it's either ingesting it at a hose clamp, a pinhole in the cores, or the head gasket is failing.

The best thermostat I've found is the Stant Superstat, which dampens any oscillation upon opening, and is supposed to have a 'failsafe open' design, so it doesn't get stuck shut.

 

[John Wood]

Not to stir up a hornets nest. ... but I have used the orange (OAT) coolant going on 8 years, (with one 5 year replacement), in both EEK cars. I use the 5 year (HOAT) in the 96 mini-van 3.0. That is a greenish/yellowish colored product which is probably what you bought. As mentioned by one of the posters, the key is to totally flush out all the old coolant and the overflow bottle. I ran 3 cycles of clean water through my system before changing over and I acid cleaned and thoroughly flushed the overflow bottle. Why did I do it? There were a couple of reasons but primarily I was looking for the 5 year change interval. Over the years I saw too many cooling systems neglected and people tend to forget about the 2 year change intervals with the original green product. Also, the HOAT and OAT products provide superior lubrication for the water pump bearings.
Never did I experience any of the horror stories about the orange coolant that I have heard about. Most of those occurred on GM cars and GM was the one that pushed the orange product initially. Go figure.

The nice thing about the 5 year product was that when I drained the system after 5 years, there was no rust and no discoloration. Personally, I think it is the way to go. The stuff you bought should be fine but don't trust mixing it with what is in there; flush the system and clean the overflow container.

I guess I should mention that it is best to just disconnect the hose going into the water pump when you flush and drain. The draincocks on older radiators tend to leak once they are opened. That is usually from rust or debris getting on the sealing surface.

 

[neon98rt]

i was told as long as the coolant is slippery it is fine. Or chunks of whatever in it then change it.

 

[valiant67]

There are really two things that factor into when to change coolant.
First is if it still tests to the specified level of protection. Second is if electrolysis is occurring. I guess third would be if it's contaminated.
I heard from a pro-GM mechanic that electrolysis was one of the big issues with Dexcool. Cooling was still fine, but the electrolysis was eating stuff (aluminum) up.

 

[John Wood]

There are really two things that factor into when to change coolant.
First is if it still tests to the specified level of protection. Second is if electrolysis is occurring. I guess third would be if it's contaminated.
I heard from a pro-GM mechanic that electrolysis was one of the big issues with Dexcool. Cooling was still fine, but the electrolysis was eating stuff (aluminum) up.

I heard similar reports, but supposedly the electrolysis only ocurred if the coolant stayed in the system beyond the 5 year change period. The same situation can occur with the old 2 year green stuff, especially after 3-4 years before replacing it. I think the newer 5 year products are a little more resistant to the corrosion by electrolysis. I could swear that the pink stuff in the Toyota has even a longer change interval but I'll have to check the manual to be sure.

 

[duncan1437]

just to complicate it further, i just noticed that the principal Prestone coolant product differs in canada and the USA. in canada its called Long Life Antifreeze/Coolant and in the USA its called Extended Life Antifreeze/Coolant, and it looks like the chemicals differ and the colors differ.

i'll call prestone canada tomorrow and ask why.

thanks for all the comments and i welcome any more coming.

 

[Musikmann]

What about buying the MOPAR coolant recommended by your local dealer? I don't know what company makes it for Chrysler but that is what I've always used. In nearly 19 years and 181,000 miles I have only replaced the radiator one time because the original developed a leak. Both were/are the Mopar brand.

 

[B10alia]

Mopar coolant is a gouge. Just use the green, personally, I like Peak. I buy undiluted and dilute it myself (use distilled water). I recommend the Stant Superstat if you're doing a t-stat. It seems to live up to what it promised. Even if it didn't, the jiggle valve saves at least some headaches on bleeding.