I drive a Toyota which doesn’t use the traditional green coolant. I have always used the Toyota red factory coolant. I’ve noticed that now there are “universal” coolants at the auto parts store that claim to work for all car makes. Do these really work for every kind of car, including Toyotas, without compromising anything?
No, some are formulated for aluminum radiators. If you put the normal stuff in an aluminum radiator… not good.
I would check out a Toyota car forum to see what generic substitutes you can use for your particular make/model (they do make generics for aluminum radiators, too). You can use them, but you have to know which one to get.
And many engine blocks are now aluminum. My car uses the orange Dex-Cool that GM puts in their aluminum block cars. Some of the guys on a car forum I frequent say that you can switch to the standard green stuff after you do an engine flush. Why anyone would do this is beyond me.
All agree that mixing the 2 kinds of coolant is a VERY BAD THING. It is also important to make sure that you get all the air out of the system with some of the special coolants.
No. Some car manufactures specifically call for silicates in the coolant, while some expressly forbid it. No way for a universal formula to pull off that trick.
The three main types of antifreeze, distinguished by their anticorrosion additives, are conventional (usually green), OAT – organic acid technology (most famously Dex-Cool [orange]), and HOAT – hybrid organic acid technology (often yellow/gold). While the antifreezes themselves are chemically compatible with each other, the additives can cause problems in the wrong environment. Some additives are known to dissolve certain plastics, some are known to dissolve radiator solder. Varying from the type of antifreeze specified by the manufacturer runs the risk of potentially serious problems.
Note that color is NOT a reliable guide to which type of antifreeze. It’s simply dye, and different antifreeze manufacturers use different color schemes.
This chart from Zerex indicates HOAT for Toyota and other Asian cars through 1995, then OAT from 1996 on.
OAT (Dex-Cool) antifreeze is a little fussy in that it must be AT LEAST 50% of the antifreeze/water mix (seriously, 49% is problematic) and the system must have ALL of the air purged. Failure to adhere to these guidelines is behind the problems with Dex-Cool. If they are followed, it works fine.
Lots more info:
http://www.eetcorp.com/antifreeze/antifreeze-faq.htm
http://www.counterman.com/Article/61862/17th_annual_technical_forum_antifreeze.aspx
This was the way to avoid the problems with Dex-Cool before it was understood that proper concentration and proper air purging would prevent the problems. It meant giving up the long-life protection, but years ago seemed a reasonably attractive option.
Why do you have to chnage the coolant? (if you have an aluminum block and an aluminum radiator)?
Can you just add an extend-type fluid to the coolant?
In theory, I suppose so, IF you can find the right additive fluid for your car and the antifreeze that’s in it. Nowadays I imagine that’s quite a big “if.” In practice, there’s the concern that the old fluid has contaminants which will only be removed by flushing. In 35+ years of professional auto repair, I have never known any shop to use a coolant additive as an alternative to flushing the system. I think such additives are marketed to do-it-yourselfers trying to minimize the cost, but are scary to shops that are expected to guarantee their work.