Volvo re-designed the oil trap sometime between the 1987 and 1990 model years of the B230 series engines. The improved oil trap is about twice as tall as the earlier model, and I think it must do a much better job. At least you have twice as much volume to plug up! It is more difficult to remove and replace with the intake manifold in place, but I just did one in a half hour. The new oil trap is Volvo part number 1389430. It can be identified by the flange on the upper end to slide a tinnerman nut onto for securing the engine wiring harness. If I had to buy one, I would buy the improved version in spite of the greater difficulty in removing and replacing. Don't forget to get the new (shorter) S tube with it, and a new o-ring for sealing between the oil trap and the block.