heater not as hot as it once was

The plastic coolant overflow tank under the hood has "max" and "min" graduations. You can find this tank by following the hose from the radiator to the tank - the fluid in the tank is likely reddish, and it's the biggest tank under the hood. Compare the coolant level in the tank with the graduations. Note that there may be "hot" and "cold" graduations and you need to pay attention to that. If the level is okay, with the car COLD (i.e. has been turned off for several hours), take the radiator cap off and check to see that it's full. If the car passes those two tests, you likely have no problem, barring a blockage in the plumbing that leads into the cabin.

What sometimes happens is that the baffle or "air valve" that directs cool air into the car sticks open, making the cabin temperature drop. It's something to investigate if the coolant level is okay.

Yes, if you need coolant, you have to use a hybrid. Toyota's coolant is specially blended with water from Mt. Fuji and then blessed by Sumo wrestlers, which is why it hits $20 a gallon or more. You can probably buy aftermarket for cheaper, but considering the investment in the vehicle, I winced and paid up for the Toyota junk.

With tongue NOT in cheek, I'd say pay a little (not a lot) more and get the Toyota coolant, but check out the cooling system first, either yourself if you have the knowledge to know what you're looking at, or with the help of a radiator shop.

Rice wine was also added and the bottles massaged while they aged in Kobe. ;)

The new Toyota pinko has 50% water already added. Because the organic acid doesn't like tap water much. Expensive way to buy distilled water I'd say. With the 02 I think you need the pinko. But if you have an older car and can find the 2-year red coolant then use it.

The pinko coolant was a copy of the GM 5-year Dexcool organic acid coolant but lacks the 2EHA acid, so the system corroded a lot more. But it's a 2/5 year trade off.

No, thermostat and coolant I would still use Toyota. The Prestone All- Makes coolant has the 2EHA acid, and if you have cheap plastics in your Toyota's cooling system it will get plasticized. Since you do have cheap plastics in your Toyota, don't use it.

Possible, but you'll overheat first. Suspect an stuck-open thermostat that lets out too much coolant to the radiator.

A bad thermostat, or the valve that flows heat to the heater, a blocked heater core or to much antifreeze will reduce interior heat

Also, do you have automated climate control system? It could be the control circuit that's bad, for example.

This has been a long-running theme on the Toyota Nation Web site, with a variety of opinions, ranging from YEAH Toy to Yeah Aftermarket.

Personally I go with this opinion from poster TRD VVTi: Toyota's red coolant actually lubricates bearings and seals better and lasts longer. Adding green coolant negates any of the red coolants benefits and makes it perform like the inferior green coolant.

I've always thought about using the Prestone All-Makes coolant. The only thing stopping me is the cheap plastics Toyota uses in its cooling systems. At least by the way Toyota tries to avoid the 2EHA acid, which is a fast-acting corrosion inhibitor used in GM's Dexcool. Toy put something else in place of 2EHA, and the new Pinko coolant (a Dexcool copy) is worse at fighting corrosion than the good 'ol Red. I was trying to find that lab test report about "significant [metal] weight loss" with the pinko.

Whenever I look at the Prestone All-Makes, the "2EHA" jumps out, so I put it back. Maybe it works fine as Prestone said. And you confirmed it. Maybe I 'll get to use it one day.

BTW, Prestone coolant is made by Honeywell, who is also the OEM coolant maker for Toyota, Honda, and who knows what other OEM coolants.

Yeah I know, like oil and oil filters everyone's got an opinion.

However, both the Toy Red and the traditional Prestone Green are 2- year coolants. The green has silicates that's a very effective corrosion fighter. Toyota Red/Pinko don't have silicates because the pumps use inexpensive rubber o-rings instead of the carbide seals in American and European cars.