Hello - I just purchased a 2006 Nissan Frontier (V6, 4.0L) and was wandereing if it is too late to switch to synthetic oil.

Thank you,

EP  

Also...the Frontier is at 50000 miles.  

i use 5w30 royal purple in my wifes 07 pathfinder. it also has the 4.0 v6 like your truck. royal purple claims there oil is good for 12,000 miles with a filter change at 6,000 miles so i'm trying it out and i have to tell ya that so far it pulls like a champ. i just swapped out the filter and one quart of oil 1,000 miles ago. we drive that thing like crazy too. well good luck.