[JohnTaper]

I think most aftermarket radiators are pretty similar as far as quality goes. Denso or mishimoto may be a little better quality, but it's hard telling. I usually just get them from the part store so i get a lifetime warranty.

Plastic tank radiators usually leak from being cracked or at the tank seals to the core. When you say the hose flange, are you sure it's not a bad hose or clamp? Just curious where it's leaking from.

 

[JohnTaper]

In the automatic, the torque converter clutch doesn't fully lock up until the engine gets to operating temp. The vehicle will go into final gear, but the torque converter won't be in full lock up. You won't notice this until you put in a new thermostat. You'll actually feel it lock up when it warms up the first time if you are cruising at steady speed down the road. It will almost feel like you shifted into another gear.

Get a thermostat from Honda. That is one part I always get from the dealer on any honda. With the poor heat, it sounds like a likely cause. You can order honda factory thermostats right on amazon or ebay, or wherever you prefer. Probably 30 bucks.

 

[JohnTaper]

See the light going through the rubber diaphragm in the middle of the thermostat? That is where these thermostats commonly fail. You shouldn't be able to see through that with thermostat closed. Water flows through enough to act like it is stuck open. I don't have a new one to look at, but I'm pretty sure that's the case.