I've run synthetic in my Ford truck for 18 years, and I'm a believer. I've had to have work done on the engine, but it has been minimal for an eighteen year old truck. MB USA has us changing the oil every 10,000 miles. It's hard to wait 10,000 miles, changing the oil is engrained in me. I had always heard about blow-by in turbo engines and I guess that has been addressed, along with other turbo nightmares I'd heard of from the past like problems with cool down. Blow-by was all the crap and carbon that blew by the rings because of higher compression. Years ago, guys I knew with turbos (a few, mainly race cars) changed their oil often. I really want to change the oil, but I'm not going to. I do however, want to see what it looks like when they dump it the first time. Changing the oil is a relative cheap process when you consider the positive effect on the engine.