SR20 oil/plugs winter/summer

[EJ253]

hey guys,
i picked up an S14 a few months ago, i need to do an oil change soon. what oil should i use? its cold in utah (30 degrees during the day, 15 at night) for a while. so what synthetic oil should i be using? also, what should i use in the summer time (100 degrees during the day, 65-70 at night)?

im having some issues with my plugs also, they were gapped to .30 and boost would blow them out, now theyre .25 and at .7 bar they still get blown out a little bit. is .22 too small? also, what is the stock heat range? i want to run colder plugs in the summer, what heat range should i use? what about in winter? warmer heat range?

sorry thats a lot of questions lol

thanks,
Greg