Hi, Keegan; The only answer to this is to have the leak(s) repaired. There is no 'magic' cure. These 'additives' that are on the market are snake oil. They cause the seals to expand which might help, SHORT TERM, then all h**l breaks loose. Don't use them. In the mean time, until you can get the leak(s) fixed, I'd recommend carrying a couple quarts of 10/30 with you and check the oil level, at least, every time you get gas.
I have a 2001 Chevy prizm with 160,000 miles on it, I was told it has a pretty decent oil leak, I just got it changed and they said there was less then a quart of motor oil left, what kind of oil should I use to maintain the oil levels, and are there any recommended engine repair additives I should use?