Conventional vs Synthetic:
As has been mentioned, if your driving style means you HAVE to dump the oil every 3 months or 200 hours or whatever the severe service recommendation is, then conventional is fine.
If you have extreme cold or sustained heat, then synthetic has a definite advantage. It flows better in extreme cold and resists breakdown at higher temperatures.
Extending oil changes: I have seen plenty of empirical examples where people have extended oil changes on conventional and not just synthetic. Conventional oil has improved over the years. Once upon a time you would need synthetic base stocks for extending oil changes, but conventional base stocks have improved as have additive packages.
But you can only greatly extend oil changes with oil analysis. Here is a link to my oil analysis:
http://www.taurusclub.com/forum/82-...e-oil-6200-miles-12-months-5.html#post2679929
Over 9000 miles and more than a year. No problems back then and none since. And those 9000 miles included a lot of short trips and sustained highway driving at over 100f for several hours at up to 90mph - maybe 2000 or so of those miles. You do need to note that living in CA, my oil gets up to temperature more quickly and even if I had two weeks of exclusively short trips, I would then have a 1 hour or so trip on the freeway.
If you don't do oil analysis, then the information provided by major brands is helpful. Mobil warranty M1 full synthetic for 10,000 miles and their M1 EP for 15,000 miles. Both for 1 year. They may very well want you to spend more on synthetic and could warranty their conventional oils as well. Who knows? But the fact is that M1 can be had for the same as conventional oil after the $12 rebate and it is guaranteed for 10,000 miles, as is Castrol Edge. This applies to non severe service and it is good to read up on their definition of severe service.
Is synthetic better? Technically yes. SAE testing shows it leaves less deposits, resists breakdown better, results in less evaporative loss. All the things that leave your engine as close to factory clean if you extend oil changes. Will it matter and if so at what mileage? I don't know, but since I've always gotten full synthetic for $1 a quart or less and want to extend my oil changes, and have short trips, it's a no brainer for me to use the oil that minimizes wear and maximizes cleanliness.
Do tears in an oil filter matter? Who knows if a combination of events will lead to engine damage, or how long it will take for the cumulative effect of unfiltered particles to damage bearings (45% of bearing failure is due to dirt (reference MAHLE / Clevite)). But there is no reason for me to buy filters from a company who is clearly having quality issues. My own cutting open of Motorcraft and Bosch filters leads me to the conclusion that they weren't the best choice for extended oil changes.
Everybody is free to decide what is best for their situation. Go with the manufacturer recommended mileage or time or go even less. Use the manufacturer semi syn oil or don't trust it and use something else, approved or not. Use the manufacturer specified oil weight or have a reason to use something heavier. Use a Motorcraft or a Wix filter and stay away from Fram. All different decisions have been made by various owners for their own unique individual reasons.
My own decision to extend oil changes using synthetic 5w30 oil I got for next to nothing was confirmed by spending $12 on an oil analysis. In other words, using data not supposition or emotion. In fact, the only emotion I have ever had about this is fear of extending the oil change beyond a certain point. And my decision to go with a Fram Ultra was based on a desire to not change the filter at every oil change and determining that a synthetic long life filter was more appropriate for this decision than a cellulose one.
For my personal situation, saving time and resources and not dealing with used oil as often was important to me. So I decided to see what was possible, which meant understanding the basis of manufacturer recommendations, research on what others were doing and a used oil analysis. Only then did I decide to extend my oil changes.
I'm happy I've made good choices for my situation. And it also leaves me more time for other more important things like changing the fuel filter.