I only make about 3 purchases a year at BP and I have a rewards cards with them but it sounds like you guys are talking about a credit card because I sure can't buy fuel with a rewards card. So am I to understand that they have credit card that generates store credit instead of airline miles or Discover's cash back? If so, I may need to check into that.
They do have a club visa that gets you more points. Points with just the rewards card can and do expire. If you call Springfield office or go to customer service they will put points back on your account. I've had them do it several time when points expired. I save them up to help with bigger purchases.