I just changed the oil in my 258(actually for the first time since I bought it). I put in 10W40. Since I started driving it I noticed that the pressure drops off lower then it did before after driving 15 min. I also noticed that it seems to be noisier(lifters or valves maybe). I've never noticed it being this noisy and I've never noticed the pressure drop like that. I've been using 10w30. Have I put the wrong oil in or is all this a coincidence?