My 2003 nissan maxima has 80,000 miles. What grade oil for florida should i use. I have slight pinging noise?

I purchased my 2003 nissan maxima at 72000 miles and have had my first two oil changes done at mobil lube express. Since then i have notice slight pinging at about 2000 rpms. I was told that my timing chain tentioner may be going bad. Or is it that the oil grade 5w30 they used is too low for that amount of miles?