Almost a year ago (last March) I got new TR55'* in my car when I did my UIM swap with Bill Buttermore. It REALLY woke the car up again, but over the past year I noticed, gradually, that it didn't seem to have the same pickup I remembered. Well today I dropped in some brand new TR55'* and GOOD GOD! My car feels like a new beast! I had no idea so much could change over only 10 months, but I was shocked how the car woke up again. Well my car by NO means felt slow, but I knew it wasn't feeling like last March.
Here'* a shot of one of the plugs after 10 months (20,000 miles). To me they seem as normal plugs should. The gaps averaged between .061" and .063". Specs say .060" by the way.
So, is this normal? How often do you guys change yours? God knows I'll be on a 3 month rotation since I paid less than $12 for the set.