Don't use Seafoam on anything over 150 K miles or not maintained well. I used it on a Honda I bought with 170 K miles. Car didn't have the right plugs in it even when I changed them. Gave it a slight CAM sound though lol. But after running the Seafoam (I did the full treatment of gas tank, put in the oil for 100 miles before changing and running it through the intake), I had oil leaks and the connect rods started making noise. Sometimes that carbon is needed. It seems to fall under the same line of changing the transmission fluid and filter on a higher mileage vehicle. If it hasn't been done, leave it alone.
