I have an 07 Civic SI with 263 K miles and I have never done any engine work. I run a home-brewed synthetic blend 3syn:2conv and change my oil every 10,000 miles and my WIX filter every 20. The only work it's needed is a replaced starter replaced serpentine belt and two idler pulleys besides 2 clutches and tires. Nope I've never done a valve adjustment still starts idles drives strong no ticks but knock on wood I think I better soon. I run techron fuel cleaner about every 10K and add 4 oz. of Lucas syn oil stabilizer every change. K20Z3 is a 300K engine if you leave it stock at 200 HP.