HIllo all. I need a little guidance for my 86 Pontiac Fiero 2.8 v6 the motor is original with 92k miles. I have been using pennzoil pure platinum 10w -30 and change it every 6 months as it sees less then 3000 miles pure year. My dilemma Is the zddp content. Is it enough or would shell rotella t5 be a better choice? Also what about the rotella t6? Would 5w 40 hurt anything as I am in orlando and it is never cold here. Please let me know what your thoughts are on this and thank you for your help.