This has been asked and answered before many times but I will give you my fill since I am here anyways.
He's probably just trying to feed you some BS so as to scare you in continuing to go to him for service, plus he might be old school and thinking of the very first synthetics on the older engines. Synthetics now-a-days are a good oil to use providing you keep with well known/quality brands, worse case is that they will be no better than the standard 5-W20 used by Mazda. Remember, all 5-W20 oil (motorcraft included) at the very least are a synthetic blend. I have yet to see a 5-w20 that has been pure dino oil. So technically the oil you are using is already half way there from being a pure synthetic.
As for the K&N Oil Filters, you are always going to have to have some compromise on flow rate vs. filter quality. K&Ns are decent oil filters that filter quite well but are really known for their high flow rate (mainly the bypass flow rate, one of the highest rated amongst filters). KN Oil Filters use a resin covered filter type media, I believe similar to the PureOne filters (which rate well too). This allows the filters to have a high flowrate yet still maintain a decent filtering quality. I have yet to have an issue with my KN filters and I have used them in my older 87 Honda Accord when I had that. The thing I enjoy about the filter the most is the welded nut at the end of the filter making it easy for removal in tight spots. And if you haven't looked under your car yet, you should. The amount of space available for filter removal is dismal at best. My first oil change I broke a filter wrench and punctured the filter upon removal attempt (Required jabbing a screwdriver through the filter and removing it that way). Of course it didn't help that the factory tightened too much and the plug too little (was able to remove plug with my fingers).
:seeya:
Paul
On a side note, where in Puerto Rico do you reside? The wife and I visited PR in June for the first time and loved it (Stayed at the Marriott in San Juan). We plan on returning again next year. I saw tons of Mazda3s but maybe only one Mazda6 when there. Oh, and I thought that I drove on scary roads (DC, 495 Beltway, 270, etc) but you guys take the cake! I loved seeing how one car stopped in the middle of the road and "backed in" to a one way garage to park, even though the entrance was the next turn. You guys are crazy!
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