There may be alternatives, but the price difference between them and Super Long Life Coolant from your Toyota dealer is not worth the risk, from my point of view.
I've also seen chemical reactions occur when people mix coolants. Unless your going to flush-out the entire cooling system with distilled water - I'd just stick to OEM coolant for a quick drain & fill. Whatever you save from the cheap stuff at Walmart, you'll be losing in time spent doing the job correctly - IMHO. Then again; if your time isn't worth anything - go for it.....
The Petroleum Quality Institute of America has some helpful information on their website that will help you understand the importance of using the correct coolant in your vehicle. Additionally, John Kelly of Weber University and The Car Care Nut both have YouTube videos that will help you understand and make an informed decision on coolants for these vehicles. Failure to use the correct coolant will significantly increase your cost of ownership.
If you read Toyota's recommendation in the Owner's Manual, you may come to the same conclusion as me. The recommendation: I read that, and my conclusion: I'm not bright enough to find a suitable alternative, just stick with the Toyota stuff.
What sucks is Toyota is not open on Sundays. I had to top mine with the asian red/pink 50/50 premix. Hope it does not destroy the engine eventually. The guy at the store said it was OEM. But I trust no one anyway.
