Ok, from prior posts, I installed one of the Iridium Plugs and also changed my oil with Amsol 10W40W. Can't say I can notice any difference compared prior to the changes. I have read all kind of great results with others, but I notice no difference. I can't tell my shifting is smoother with the Amsol or can I tell if fan runs less and in cool weather, the engine still takes a while to warm up at idle and still have to keep choked until it warms up somewhat. The fan didn't run much proir though to the oil change. I am not unhappy making the changes, but just letting others know, these items are not miracle workers from what I can see anyway.