I agree, it's hoarding. In the OP's case though, he has estimated (before buying) how quickly he'll use these up so it's not quite the same. People hoarding gallons upon gallons of oil for vehicles they might now own in the future or for doing an oil change on a neighbor's vehicle because they have oil is strange.... If a neighbor asks me to change their oil, my response would be "you want me to run to O'Reilly's with you to get the stuff or if you're going to Walmart soon, I can tell you what to get?" (we have an O'Reilly's in our small town but Walmart is ~15 minutes away).
I can tell you exactly how many filters I have in my "stash": 0
Oil ? Ummmm, about 3/4 quart of 5W-20 Magnatec (wife's car uses 4-1/4 quarts) and 1/2 quart of Magnatec 0W-20 (son's car uses 4-1/2 quarts). I do have 3 quarts of Castrol ATF for my G35 but it takes 3.5-4 quarts for a drain and fill and I never remember to get an add'l quart.
I can tell you exactly how many filters I have in my "stash": 0
Oil ? Ummmm, about 3/4 quart of 5W-20 Magnatec (wife's car uses 4-1/4 quarts) and 1/2 quart of Magnatec 0W-20 (son's car uses 4-1/2 quarts). I do have 3 quarts of Castrol ATF for my G35 but it takes 3.5-4 quarts for a drain and fill and I never remember to get an add'l quart.