I used mobil 1 synthetic 10/30 on my last oil change, but noted that the recomended oil on the owners manual is ACEA A2 OR A3 and the one I used is ACEA A1......is this a problem ? please advice

 

2001 E320 3.2 engine

 

I don't thing it will do any harm at all to your engine at all. Just make your next oil change half sooner at 5,000 miles and use Mobil1 full synthetic 0W-40 european formula that you can find even on the shelves of your local Walmart for $6.27 per qt.
Bernard