Just something to consider...
Late '90's to early '00's, some of the small 4-cyl Japanese engines (especially Toyota, and I believe Honda as well) were having lubrication problems. I began reading about these problems by the mid-late 00's. It struck me because by then both Toyota and Honda had a lot of experience designing engines and very good track records with ruggedness and reliability.
IIRC, the talk at the time attributed the problems to a push to raise combustion temperatures to meet emmissions/milage goals. That lead to local overheating of oil to the point of degradation and sludge and/or varnish that ended up restricting flow through small oil passages, which then set up for a positive-feedback cycle of higher temps and even more damage to the oil, then to oil starvation and the resulting wear/damage. Many folks at the time proposed/reported that engines run with synthetic oils didn't suffer, and I seem to have some recollection that some of the automakers were issuing TSB's recommending synthetics for certain engines.
I also recall that around that time GM was having some sort of problems with overheating of a Corvette engine during final testing before release of a chassis redesign that didn't leave enough room for a big enough radiator. The reports at the time were that they were able to "solve" that problem with synthetic oil, i.e. dropping the operating temperatures in the engines sufficiently to match the cooling ability of the compromised radiator. (Note that by "operating temperatures" I mean local temperatures at critical components, not the overall engine coolant temperature.)
At the time I just interpreted it as one more reason to go to synthetics. Between the synthetic oil's tolerance for higher temps and lower operating temperatures, it seemed to give further justification to my existing bias toward synthetics. I paid special attention because I typically drove Toyotas with 4-cylinder engines.
I revisited this issue again a couple of years ago. My sister-in-law and her husband had a 2001 Chevy Prism (re-badged Toyota Corolla) that they had for several years, after inheriting it when her mother died. They live in Manhattan, didn't use it often, were tired of paying for garage space and insurance, and the A/C failed (2nd time) and were told it would cost another $1200 to fix it. My son had just graduated from college, so they gave it to him, since they knew that I could fix up whatever might need to be done. He drove it from NYC to Wisconsin (~1000 miles), where I would go over the car for him. When I looked at it, there was no oil on the dipstick, and I was only able to drain ~1.5 quarts! The temp gauge showed normal temps, and everything seemed to be working OK, but I needed to get to the bottom of this. He didn't check the oil before he left, but my sister-in-law said they drove it very little since they last had it serviced professionally. I went on-line to find hundreds of complaints for that engine/generation (high oil consumption, in many cases 1 quart every 250-500 miles). The issue was clogged oil-return passages behind the piston oil-rings. When I tore it apart, I found cylinders and bearings in good shape, but most of the oil-return holes (IIRC there are 6 or 8 per piston) were clogged or nearly so. On further research, I found some sources of pistons designed or modified with more, slightly larger oil passages, as well as numerous instructions/YouTube videos showing how to modify stock pistons. I contacted one guy who was selling pistons on ebay, made to his design, who claimed that he was selling many sets each week for this engine and others with the same problem.
This car only had 80,000 miles on the clock, but for both my mother-in-law and sister/brother-in-law, they used it mostly for short trips. The temperature cycle of that driving pattern is notoriously tough on oil, providing lots of time for heat-soak of oil that hasn't been run long enough and hot enough to drive out all of the water and combustion-gas contamination from cold starts.
Again, I found lots of Internet chatter suggesting that engines running synthetic motor oils were not suffering the same fate.
FWIW, not long after I fixed that engine, my daughter's '96 Corolla had a problem requiring me to tear the engine down @~150k miles. That engine ran on synthetics (Mobil-1) since ~75k miles. The oil passages in those pistons were fully open, with only a light coating of varnish. (Note that this engine was designed before the push to raise combustion temperatures, so it's not an apple-to-apples comparison).
My recommendation would be to pay for the synthetic. You can get Mobil-1 at Walmart for ~$26 for a 5-quart jug (I presume they have Walmarts in Arkansas!). While I didn't search for problem reports on this particular engine, and Mazda makes good engines, it's a still a small 4-cyl Japanese engine, in an overall warm/hot climate, making short trips, with a desire to minimize oil change frequency, and with a driver who doesn't pay much attention so might not catch any signs of problems until it's too late.
I personally pay the extra couple of dollars for the "Advanced" "extended mileage" version (I think the bottle has 12,000 or 15,000 miles marked on it - NOT the "high mileage" version that has 75,000 miles on the markings). I then change it once a year in each of my cars that are driven ~12,000 miles per year in engines with over 100k miles with drive-times only rarely less than 25 minutes.
I'm not a pro, and have no connections whatsoever to the oil/lubrication industry. But I've been following/researching synthetic oils since they were introduced, including numerous conversations in the mid-late '90's with a guy who ran an engine oil analysis lab in Cleveland when I lived there. Back in the '80's and '90's oil was more problematic than now. I used to change conventional oils every 2000-2500 miles. I switched to synthetics, and sent several samples for oil analysis under progressively longer change intervals (same car, same driving patterns). I went over results in detail with the guy at the oil lab. When I got to 9,000 miles, he could then point to the earliest evidence of oil "stress", and said he personally would have been perfectly comfortable running it for another 3,000 miles.
Both synthetic and conventional oils have improved since then. I agree with other posters that in most cases conventional oil will do just fine at 5,000 miles/year under "normal" circumstances. However, I think it would be prudent to spend the extra $10 or $12 per year in this case.
