Thanks for all the answers, folks! I would have replied sooner, but I thought I'd get an email when someone replied, like with Quora. Anyway, everyone's input is appreciated. For what it's worth, I used Mobil 1 in my Saab 900 and it had gone 340,000 miles when I donated it to the Salvation Army. My research consisted of visiting various forums and reading scores of reviews. Royal Purple (RP) was rated very highly in all of the reviews that I read. I was just wondering if it was really that much better than Mobil 1. I did read that the Mobil 1 filters did not have steel mesh holding the filter media in place, so I don't think I'm going to get any Mobil 1 filters any more. I've been using Motorcraft filters exclusively in this Ford Escape. I HOPE this new engine lasts--the one it replaced had a crack in the block between cylinders 2 and 3, and coolant was leaking into cylinder No. 2. Luckily, I was still under the powertrain warranty. Over at the Ford Escape forum some people took umbrage for my reporting this problem--and I frankly couldn't believe it. If I bought a car and someone had some words of warning about a major problem, I'd want to know! It seems a number of Ecoboost engines manufactured in the UK had some bad blocks. Anyway, with the new engine, I wanted to make sure it lasts--assuming that it isn't flawed like its predecessor. I had planned to change the oil, using full synthetic, every 4,500 - 5,000 miles. I remember that Mobil 1 once had a deal that they'd guarantee your engine lasting if you used their product exclusively--though I'm sure that the warranty didn't cover blown head gaskets or broken timing belts. I just might stick with Mobil 1 for the Escape. It surely worked with my Saab!