Oil Filter Brands
Congratulations on your purchase of the 190E. I recently purchased a '88 260E which, I believe has the same engine. Two weak areas on the 2.6 engine are the valve guides and oil leaks from the front timing cover. Other than that, I think it's a good solid engine.
I would also caution against using Fram oil filters. On my Volvo board they are referred to as the "Orange Kiss of Death". Apparently, they don't have the anti-drainback valve that helps hold the oil in the upper engine. I would also go with a name brand oil such as Quaker State, Castrol or Valvoline. I lot of MB owners use synthetic oil but I hve not tried it yet and with 128,000 miles I'm a little reluctant to start.
Good luck with the car.