I change oil at Spring and Fall to meet the six-month oil change criteria. Since I don't put a lot of miles on Speck, I haven't reached the 7,500 mile limit yet. If I ever did, I wouldn't worry if my oil would hold up for that long.
I use Mobil 1 synthetic oil and filters and get it on sale with rebates. The cheapest place I've found is usually Walmart. I choose Mobil 1 products because they have a good, long standing reputation and they publish the filtration specifications for their filters. Most filter companies don't. I've found filtration specs for Mobil 1 and Wix, but no others. Also, with the rebate Mobil 1 products are priced about the same or less as their competition.
I have gotten to buying supplies when I need them rather than stockpiling supplies. Filters have a long shelf life, but I'm not so sure the motor oil holds up to long term cold storage without some form of degradation. Plus, there's no rebate for stockpiling. If Mobil ever stops offering their Spring and Fall rebates, I'll likely switch to some other less expensive brand.
I do a oil and filter change in the Spring and a oil change in the Fall. Last spring I submitted my oil drain to Blackstone for analysis and the results looked positive, so I plan to continue that method. With this oil change strategy, I can purchase one 5 quart bottle of Mobil 1, use enough for a complete oil and filter change in the spring, and have enough left over for a oil change in the fall and keep the filter in place.
One bottle of oil and one filter for the year. I try to conserve resources whenever feasible. It's tempting to keep the filter for a two year cycle because I don't think I'll use up the published mileage specs on the Mobil 1 filter, but I'm not sure I'll do that. No point in risking engine damage to save on a filter, especially since I'm already extending the filter's use.
Here's my write-up on last spring's oil change:
Sunny & 60s - nice weather for an oil change.
And here's the results from my Blackstone Labs analysis:
Blackstone Labs Used Oil Analysis Results