I have 225,000 miles on my tank and have used mostly M1 15W-50 with the occassional usage of Rotella 15W-40 when finances werent as good. I purchased the car with about 40K on it about 10 years ago so I am not sure about what was used prior. With this many miles I am interested in putting Mobil1 10W-40 High Mileage in her from this point forward. Please comment on this specific product in this application... thanks!