Used OAT coolant in HOAT/IAT application

[Rochev]

I changed the waterpump, tstat, and radiator on a 2003 Tacoma. It had the original atf-red coolant. I refilled with the universal Supertech just to make sure it runs good and to move the truck, as I bought it wrecked. I'm seeing Toyotas red coolant is IAT, and I've seen that it's HOAT. Should I flush it and refill with an Asian phosphate formula? I let it run for a while and drove it around the yard, so it definitely circulated. I've always used Supertech on flushes with no issues. But now I've discovered OAT, HOAT, IAT, something that starts with an E, etc. I'm hoping to drain the rad and refill with Zerex and be done. I used almost 2 gallons of the Supertech, so up very little of the old stuff remains.

 

[CharBaby]

Personally, I don't think that you will be doing any harm by using the SuperTech(I believe it is a Dex-Cool clone) that you've been using for years. However, it is not optimal.

BUT, If you're going to drain & refill again with ZEREX Asian-ANYWAAAAY, then you'll be doing the(more) optimal thing and may want to do a complete flush and get out all of the OE + ST and put in the ZEREX Asian(RED).

There's nothing like doing the job correctly.

 

[doublebase]

I’d be surprised if Toyota red is IAT, pretty sure it is a OAT coolant, but it doesn’t really matter...I believe all Toyota’s can use the newer coolant/Zerex Asian.

 

[nwjones18]

I think I was a happier person before I learned about IAT, OAT, HOAT etc. I've been putting universal coolant in for all my coolant flushes for years with no long term issues. Lately I'm using Prestone 10yr/300k, but now that I'm 'educated' I second guess all my coolant decisions.

Personally I'd stick with your plan and run the Zerex. It seems to be prefered over the Prestone on BITOG.

 

[Rochev]

Thanks all. Yes it was much easier before I figured out the differences, now I'm just stressed out lol. I may do a couple drain and fills, that should clear it up.

 

[2EHA]

toyota red is from the HOAT era. benzoate + phosphate

dexclones rarely cause issues, that’s why they’ve been america’s universal coolant of choice for the past two decades

 

[Rochev]

toyota red is from the HOAT era. benzoate + phosphate

dexclones rarely cause issues, that’s why they’ve been america’s universal coolant of choice for the past two decades

Ironically your user name is one of the ingredients I found didn't work well in some systems. Thanks for the clarification, should I leave it as is or drain and fill again with Supertech?

 

[Jake_J]

2EHA works fine and is used in many OE coolants, what didn't work well was mid 90's GM poorly designed gaskets (with any type of coolant). Toyota red (LLC) is a HOAT and has been replaced by the Toyota pink P-OAT SLLC coolant. You've be fine running any of the Asian P-OAT coolants (regardless of color) or any Dex-clone (is Supertech) which is essentially the same thing without a bit of phosphate added in.

 

[Rochev]

2EHA works fine and is used in many OE coolants, what didn't work well was mid 90's GM poorly designed gaskets (with any type of coolant). Toyota red (LLC) is a HOAT and has been replaced by the Toyota pink P-OAT SLLC coolant. You've be fine running any of the Asian P-OAT coolants (regardless of color) or any Dex-clone (is Supertech) which is essentially the same thing without a bit of phosphate added in.

Awesome, thanks! I shouldn't have started investigating lol