I put a rear main seal in last year and it came with the rubber "noodles" and they sealed fine. I did this w/ the motor in the car and tried to use a dab of silicone on (in the cap ridges)each to keep in place while I slid the cap on...did not work as the pressure kept pushing them down as I slid the cap in place. Finally just put them in by forcing the rubbers in with the cap being carefull not to let them move or pinch(slowly!) I did silicone where the cap meets the block and pan. Dry as a bone (fingers crossed!) ever since.