Oscar increased his bet each time that he won, provided that he was losing at the time, provided that the increase would not make him win more than 1 unit more than what he was losing. I.e.: $5 starting bet. Lose 5 in a row, down $25, Win, now down 20. Bet 6. Win, now down 14. Bet 7. Lose down 21. Bet 7 (same bet when losing) win, now down 14. Bet 8, win, now down 6. At this point a bet of 7 would recover plus 1 so the bet is 7. If the loss were more than 8, the next bet would have been 9.
In other words, Oscar's Grind starts with a 1 unit bet and advances only on wins WHILE YOU ARE LOSING. In other words if you lose three in a row and win you go to 2 units. You stay at 2 until you win and if you still need to bet more to get to be even or plus one on this series of bets, you raise your bet again by one unit. And so forth. It is more gradual than the 31 method.