Everyone has an opinion is right. Mine is that 3000mi intervals are arcane. Modern autos run very clean and don't contaminate oil like they used to. I also have a new Ford diesel truck. On the Ford-Diesel website this subject has been beat to death. The fact is that oil analysis on these trucks has shown that up to 10,000 mi. intervals show little degredation of oil. Without a doubt gas M-B engines of recent vintage are much easier on oil than a diesel truck. On the other hand these are expensive engines and I personally go 5000 mi on my german machines. If I switched to a synthetic I would use the cars computer to determine intervals. Or as discussed earlier change when the climate dictates.
90 300GE 5sp