The only logical reason besides price would be internal modifications to the engine. Who here has changed the bearing, piston, ring clearances? Perhaps Import. My car gets the worst kind of treatment. All short trips as a daily. Except driving to the track and WOT for extended periods on the race track. Not to mention the water temps after 20 minutes. My Blackstone oil reports are on here somewhere. Compression is within 2 PSI from the highest to the lowest cylinder. Mobil 1 oil is doing it's job despite the non stock hp, non stock temperatures at the track, abuse, etc. Now that I've given my testimonial, Justin uses Amsoil 5w-40 european in the Racefire which isn't approved by MB and it's getting the job done.

Les