Ok. As your car hits the face of a jump the shocks compress, and then rebound. The rebound gives the car sort of a hop off the jump. If your oil is "too heavy for the springs" to rebound fast enough to give the car that hop. It may lose out on some distance. I'm sure you know changing your oil, or springs to help may change your handling in other places on the track. If your just missing it I would say go 5 or 10 wt lighter on the oil, and see where that puts you. Then match your springs to your new oil weight.