hi my name is matt, im a volvo tech in albany ny, we've seen a few cars that would lose oil pressure, you do the oring and it would be fine but on a few others it sill had no oil press. then we put engines in them, now i took an engine out of a 2000 XC70- B5244T that had this problem, rebuilt it useing all new volvo parts, (ALL!!) including an oil punp and still its loseing oil pressure. now it only happens under a load. i can let it sit all day at an idle and its fine but as soon as i take it out on the road and put a load on it it loses pressure, please help im lost and no one can help me. aaaaaaaaaaaaaaahhhhhhhhhhhhhhhh!!!!!