Hi All! I purchased a 2007 Lexus is250 in Jan 2021 with 113K miles. Immediately after I replaced all spark plugs and the PCV valve with Lexus OEM parts for preventative maintenance purposes. It now has 133K miles and I have had zero issues with it. The original owner took it in for an oil change every 4K miles, and I have done the same with Molbile1 full synthetic oil. Also, I always use 93 octane gas. 

Despite having zero issues, and the motor running smooth, is it worth taking it in to do a walnut blast of the engine for potential carbon build up? Not sure if this would be lighting money on fire given there is nothing wrong with it currently. It makes a slight ticking noise at idle, but I was told it was just the direct fuel injectors.