Has anyone tried Motor Purr Tune Up in the oil to prevent sludge problems in 2.7's? I ran some in a Chev. 305 (117k mi) for 200 freeway miles, drained and flushed the pan with a quart of clean oil. After several hundred miles since, the oil (Mobil 1 10w-30) is still clear and valve stem seal problem fixed (for now). No problems with the Intrepid yet at 150k miles. Wondering if this stuff would be good for it or just dislodge crud to plug things up downstream ("if it ain't broke, don't try to fix it")?