My bro, who drives a Altima, just recently changed his oil to Mobil 1 5w-30, but with a regular oil filter. My question is, can he run it up to 5k safely on that filter or should he change that filter out at 3.7k?

 

He should be fine.

 

Thanks. Should he switch his filter out to synthetic next time? Or just use the regular filter still?

 

Pretty much any quality filter will work fine, either for conventional or synthetic oil.

 

A quality conventional filter is acceptable for a 5k interval. For longer intervals, a synthetic element filter is more of a factor in the equation.