1999 NISSAN QUEST SE - I CHANGED THE SPARK PLUGS AFTER HEARING A TAPPING/CLACKING COMING FROM THE ENGINE & HAVING THE VAN HESITATE AT TIMES. THE OEM PLATINUM PLUGS ARE RATED FOR 100K MILES & THE VAN HAS 82K MILES. I HAD DIFFICULTY REMOVING ONE OF THE PLUGS. AFTER THE PLUG JAMMED I LOOKED IN THE "TUBE" WHERE YOU INSERT THE PLUG LOOKING FOR ANYTHING BLOCKING THE PLUG EXTRACTION. AFTER I REMOVED THE PLUG THE THREADS SHOWED NO SIGNS OF STRIPPING. I LOOKED IN THE "TUBE" AGAIN & STILL COULD NOT SEE ANYTHING. THE AREA OF THE PLUG BELOW THE "NUT PART" & ABOVE THE THREADS LOOKED MANGLED. AFTER INSERTING THE NEW PLUGS I TESTED THE ENGINE & HEARD A MUCH LOUDER NOISE. I TOWED IT TO THE DEALERSHIP TO MAKE ANY REPAIRS UNDER MY EXTENDED SERVICE PLAN (ESP). THE SERVICE WRITER CALLED & I APPROVED A $200 TEAR DOWN FEE THAT WOULD APPLY TO ANY REPAIRS NEEDED OR COVERED UNDER THE ESP. LATER THEY TOLD ME THEY WOULD NOT DO THE REPAIRS UNDER THE ESP AS A FOREIGN OBJECT DAMAGED THE PISTON/CYLINDER. THEY COULD NOT IDENTIFY THE OBJECT BUT SAID THAT SINCE NISSAN DID NOT MAKE THE REPAIRS THE ESP WOULD NOT COVER IT. I SPENT 3 DAYS FIGHTING WITH NISSAN'S CONSUMER RELATIONS DEPT & AN EXECUTIVE ASST. THIS LADY SAID NISSAN WOULD NOT COVER THE REPAIR. THE GENERAL MANAGER AT THE DEALERSHIP AGREED THAT HAD HIS TECH CHANGED THE PLUGS HE WOULD HAVE JUST AS LIKELY AS NOT HAD THE SAME PROBLEMS WITH THE SAME RESULTS. NOW SINCE I EXERCISED MY RIGHTS & APPEALED TO THE CORPORATE OFFICES OF NISSAN THE DEALERSHIP WILL NOT