Toyota Repair: Radiator Fluid Change, antifreeze coolant, coolant fluid

Question
Hi, Ted.

I have an 03 Corolla S.

I want to get the radiator fluid done.

Here is my concern. So many people out there say don't mix Yellow with red or whatever. Its confusing

I have been since day one adding when needed to, the "Prestone 50/50 Ready-to-use Prediluted Extended Life Antifreeze/ Coolant" Prestone claims its for all makes, all models, all engines, ETC and has a life of 5yrs 150,000 miles. I have been adding it to the overflow.

Now what I want to do is a simple drain and refill, not flush and was wondering if I could add this prestone to the other toyota red, since some will still  be in the engine of course, since I am not flushing it.

I have 83k miles on the original coolant/fluid (85% highway miles) and have never had a problem with overheating or anything.

Please let me know and sorry for the long question.

Have a great day, Ted!!

Answer
I would recommend staying with the toyota red fluid, it's the LLC fluid( long life coolant) which is good for 60,000 miles or 5yrs. It's not a good idea to mix different types of coolant unless you want to flush all of the old fluid out and replace it with siomething else but I still strongly recommend using the correct fluid from the toyota dealer.