6.5 is correct for the 190E 2.6 (inline 6). The inline 4 (2.3) is 5.25, not sure on the diesels. Yes, punch a hole in the filter before you start draining, since the filter is upside down, oil will make a heck of a mess if you don't. Use a center punch and a hammer. Engine should be up to operating temp for the oil change. Be sure to get a new sealing ring for the drain plug. It should be a 13mm hex (wrench) to remove the plug. Most people use a oil filter wrench to remove the filter, the best kind is the "cup" shaped one, not a strap wrench. You should be able to remove the filter without removing the air filter housing. If you do want to try it with the air filter off, there are 3 nuts, the 2 by the valve cover and one on the drivers side, kind of down low, that one actually you just need to loosen. Access to the filter on this engine is actually pretty good, there seems to be less clearance on this same engine on the 300E, which is surprising since this is a smaller chassis. And it's way better than on the 190E 2.3 with the smaller 4 cyl engine, pretty weird.
Gilly

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