Check the owner's manual for the proper weight. I doubt it will recommend 5W-30. Generally speaking, European cars call for the thick stuff. My neighbor's '91 Audi 100 calls for 15W-40 or 15W-50. For both of my Benzes the owner's manual says a good year-round oil would be 10W-40.
1994 MB E320 Coupe (199,500 mi)
1992 MB 190E 2.6 (173,000 mi)
1983 Porsche 911SC (148,000 mi)
2004 Volvo V70 2.5T (198,000 mi)
President of CT/Westchester Section