This stuff is great. I (German car mechanic for 25 years) use it in my high line cars. I mix 8 liters of the 5W-40 (Group 4) with 2 liters of their semi-synthetic 10W-40 Moly one to get a great blend that just has incredible performance. I change it at 7K miles, but it can easily reach over 12K safely. My experience with the Mobil line, regardless of what they say, is that although they are good, they just don't seem to last very long. 4 or 5K at the most, and I notice a drop in performance. IMO, the Mobil is not much better than conventional oil. The Lubro-Moly is definitely worth the price for high line cars.