I would NOT try a thicker oil. Toyota designed this engine for 0W20 oil. Thicker oil will likely not flow as well through what could be some very tight passages. Just live with the noise.
Toyota did not design their engines to only use 0w20 oil. Not sure where your getting this information from but it's incorrect. Like I stated in my other post 0w20 and even 5w20 oils are solely used for fuel efficiency reasons and the gain in fuel economy using these weights of oil is so minut that you wouldn't even notice the difference if you switched to a thicker oil. It is also false if a dealer tells you using any weight of oil besides 0w20 will void the warranty. Here's some information from Amsoil, which I consider to be the best oil on the market by far.
Truth about 5w-20 and 0W-20 Motor Oil - technical facts