Volvo 850 questions

Hello together. Have a few questions about my 850 bj. 96. The engine a 144hp 10V. 1. Question refers to the engine oil. I bought the car in March 2012 and shortly afterwards made an oil change (Castrol Magnatec 10W-40 A3/B4). Now I have found that the oil smells like gasoline. Have now heard several times and read that it can come to it during short distance operation. The car is actually driven a lot short distance. For longer rides over about 200 to 300km it comes only once a month. Should I use for this kind of use perhaps another oil? It is diluted by the bezin something. What would you recommend to me there? 2. Question refers to the oil trap. Have renewed the flame screen last week and seen that the old one was not added, but the oil was what was to it, was black and the oil in the engine “still” not. Should I perhaps want to change the oil trap completely, or is not constantly running through it? Besides, I noticed that with the smaller hose (conducter connector?) I can’t find out of the water tank.