I have been using Mobil One synthetic oil since I purchased my Subaru Forester back in the fall of 1999. It now has about 72, 500 miles on it and the engine is doing very well. The oil allows for quicker and flawless starts in the winter time when many oils thicken up so much that it makes starting a real chore. It has major advantages over conventional motor oils. They recently came out with a grade that is for hard working trucks and suv's. They site that its very advantageous for vehicles that are subject to towing, hauling and severe service in general. I am running it in my Forster now with good results. It obviously in another success in Mobil's line of synthetic oils. I have also noticed that the need for oil changes is less frequent as well. The engine has continued to run very smoothly and quietly.The downside on this oil is that some may consider it to be cost prohibitive as it averages about 5 dollars per quart. Personally though I have to consider the extra money to be well spent when I examine the overall benefits of using this synthetic motor oil.