Hey...about to do my new cars first oil change since I bought it. Now the oil cap suggests 5w-30 and it only has 48,XXX miles. I am also going to switch to Mobil One synthetic (don't know what is in there now, reg or synth.). Should I stay with the 5w or move up to 10w? I live in san diego...so it doesn't get too cold.

I looked around on the forums and no clear answer was given.