My current fill is NextGen MaxLife 5w30, which I chose to help with a rear main seal leak/seep and because of a MIR, which made it practically free. My previous fill was Castrol GTX HM 5w30, which turned the leak into a seep and pretty much eliminated all driveway spotting. Since switching to the NextGen MaxLife, the seep has reverted to a leak and I am now finding a new quarter sized drop of oil on the driveway every morning. However, I only have a few hundred miles on the current fill and am waiting for the MaxLife seal conditioners to kick in and have been told that the higher HTHS in the Castrol may have also contributed to the slower leak rate when it was in.