i have a thunderbird year 94 lx 4.6 v8 and the engine already near it's 150k mileage. the engine doesn't "eat" much oil and i have always change the oil at about 2.5 to 3k intervals. i have use M1 when i got the car about half a year ago at 130k mileage and then produce an oil leak at the oil sending unit which cost me about $250 to fix. ever since then i have using the valvoline max life and just recently doing a Auto-RX treatment. halfway through the treatment the oil pressure maintains fairly high and the engine runs smooth. anyone have a suggetion on what oil should i used or just stick with maxlife? $$$ is not much of a concerned to me because i drive a little hard on this bird and wanted the engine to last me another few more years. i have always use k&n oil filter though. thanks for any comment or suggestion.