Ever since I bought my 2008 Ford Fusion in April, I've noticed a loud knocking noise. The last oil change (Freebie) at the dealer, I asked what kind of platinum tip plugs to use. The service advisor told me only use Motorcraft or Autolite Platinum Tipped plugs. I asked about Bosch, and he said NO! The above plugs were the only ones to use. Well, I found the Autolite Platinum Tipped plugs at Walmart for $4.65 for a 2 pack. I thought great, normally they run that price for one plug. Oh by the way, the dealer wanted $17.85 for the Motorcraft Platinum Tips. I about croaked right there. LOL Well, at 5,734 miles, I changed to the Autolites. I have already noticed a huge difference in power, hardly any knocking engine noise, and on cold engine runs, the transmission doesn't drag like it used too. When I pulled out the factory plugs (Motorcraft), there was hardly any firing tip (the size of a sewing needle), and burnt ends. I was not a happy camper about this. Also, the service advisor told me that Ford built my I4 2.3 liter engine to run hot. I don't understand this at all, and neither does anyone else that I've told this too. Overall, I'm extremely happy with the changes for such little money. I can't wait to check on my fuel economy now.