Replaced cap, went in and got my oil changed and said my radiator needs a new cap and the radiator itself is not leaking, signs of leakage is at cap.
Bought another cap, still same result.

Everything is soo slight, the temperature moves so slightly it is almost impossible to see but i know my temp gauge and where its supposed to be. Also it only moves during the day when temperature in az hits over 110, I am guessing i am low on coolant so a simple re fill with the toyota coolant will fix my problem. But the slight leak is really annoying me cause sometimes it gets on my painted covers, just want to know if there is a cheap fix for this before i spend 200+ on a new radiator. The car is not overheating, and the leak is so minor i add about 1 jug coolant every year. Any suggestions?

 

you clean off where the seals go? sometimes that has a build up and keeps it from sealing right.

also, you could get a higher temp rated cap. has a stronger spring

 

Have the same problem long time a go. Believe me, I will change the radiator cap with the OEM Lexus Cap and kept doing the same. I decided to change the cap of the reserve cooland tank and that resolved my problem of the cooland leak of my car had. Try to change that cap before changing the radiator to see hat happen.

 

I forget this 2. Cut the hose that go on that cap just a little to take out the old big hole and re install in the new cap.