Seven, I wish you the best of luck. But, it is more then just more oil. I can't say what your houses do, but even if it if 40-42 ft of a THS shot, you will see a big difference at Nationals. The big thing needed, which sadly I was lacking last year, is consistantcy. You have to repeat shots, especially at the beginning of team event. Also, the USBC Open start with a totally fresh shot for team event, so you potentially (since I don't know your style of bowling) could see some snap at the start since the backends are clean. Your best prep would be to see if the house that puts out the longer oil would put down the actual USBC pattern for you, once it is released. While your house can't duplicate it 100% exact, it will give you some idea of how the lanes will react and if you bowl enough, how they will transition. But, also keep an open enough mind to see what ball reaction you have at the stadium once you are there, and make moves/adjustments off of the line you threw in your hometown practice sessions.
Jorge300