I recently purchased a 2013 gx460 with 101k miles. After driving 1k more I noticed a noise that sounds like valve clatter on start up. The oil level is good and it goes up in frequency with rpms. I have attached a video of the noise and its location. Should I be concerned or is this normal? Thanks in advance.

 

Audio does not provide enough definition to draw any conclusion ...

 

Not to get into an oil discussion ... but I run 5w-30 versus the recommended 0w-20 ... since the first oil change. At your mileage this may be a welcome change ...

The valve adjustment on this engine is pretty rock solid ... so you may be hearing the fuel injectors ... hard to tell based on the posted audio.

 

I agree with the previous responses, too much ambient noise from the fan to make anything out. If it goes away when warms up I would not worry too much about it. The GX is equipped with hydraulic lifters so there is no adjustment. Lifters can get sticky on neglected engines and cause valve clatter, if confirmed you can either try to do a cleaning cycle on the engine or replace them (not an easy task on a V8 though).
It can also be some injector noise in which case you will eventually get a misfire code. Check if the noise is there when warm and try to post a video with a bit more clear sound. You may also try find some videos on the tube and compare noises to yours.