ANTIFREEZE - VERY Important - glad I didn't forget this. Don't make the same mistake I did by using the green antifreeze. One day I looked and my coolant had turned completely rusty. The green stuff contains silicates and japanese engines hate silicates. If the coolant gets tired your block will very badly corrode. Stick with the Toyota Red coolant, which has a very different chemistry made especially for your motor. If the truck currently has green, yellow or orange coolant, you have to be very careful to thoroughly flush all traces out of it with several changes of water before filing with 50-50 Toyota Red and DISTILLED water. The different coolant types do NOT mix well. Also, tap water will cause scale and can cause corrosive byproducts to form. Stick with distilled water only. Your last flush should likewise be with distilled water, as some will remain in the heater core and various nooks and crannies. There is a draincock on the side of the motor and it helps to pull the heater hose to get a good flush.
http://www.toyotanation.com/forum/80...e-posting.html
i found this post with the link above. i haven't used the red coolant and neither did my mechanic...is this something to be concerned about?

 

:jessica: It depends on just what year vehicle your running .

All my older 22REC engines I have been running the off the shelf green antifreeze for years.

like anything else antifreeze needs to be changed the newer long life coolants being aimed at the lack of maintenance by the average clueless auto owner. No matter what hype is used to market it.

With no ill effects as far as I can tell after tearing down a few of these engines over the years.

I now have 2 of the 3.4 engines that have run the Toyota red since new and I see no reason to change.

I don`t know if they teach this any more in school but if you mix the colors Red and Green it makes a nice brown color now depending just how the 2 coolants are mixed it looks like a nice rusty brown color.

 

from everything i've ever read/learned in regards to coolant. it is completely okay to upgrade green-longlife, but not okay to downgrade. I'm fairly certain your '93 would have come with regular old green from the factory, so it's okay to stick with that.