I see quite a bit of chat about adjusting valves. The most common indicator is that they are noisy. My FJ62 with 188K sounds smooth as silk, but it does seem that fuel efficiency is down a bit. I checked with the dealer who does my work. I asked the three mechanics with signficant 3FE experience about adjusting the valves, and the consensous was if they aren't noisy, don't mess with them. Are they right?