I bought my '96 Roadmaster wagon with 90,000 miles on it back in 2006. At the time I tried various oils and found good results with Rotella 10W-30 or 5W-40 and stuck with those for several years. Eventually my rear main seal started leaking and I decided to give Valvoline Max Life Blend a try. It definitely slowed the leak down, sometimes it would even stop. After a couple of years I switched to the full synthetic Max Life and the leak went away for good (so far). The car now has 223,000 miles on it and is not leaking on the garage floor at all and I haven't fixed an oil leak by changing parts for several years. At the worst, my leak was just a drip that left a dark spot on the garage floor, not a puddle.