I have run M1 0W40 European formula, AMSOIL, and other high quality oils....they do make a difference. However, that being said, with these turbo cars it is better to change the oil more frequently. If your lab says your oil is still good until 7000 miles, that does not mean another engine/turbo will replicate your results. Why roll the dice? It is severe service, after all. Compared to the cost of repairs, replacement, and labor, oil and filters are inexpensive. Driving patterns, turbo warm-up cycle, ambient temperatures all play significant roles. For instance, using 5W30 M1 changed every 3000 miles, a commute in Florida on the interstate for 70 miles preceded by a turbo warm-up, produces very little stress on the oil. I have seen VF40's go 150,000 miles with no observable wear in that scenario. In Maine, at 0 F or below, it becomes even more important to do adequate turbo warm-up. If you are uncertain how long to do this, you can use the available software and your laptop computer to observe the engine temperature sensors as the engine warms up.