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.
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