if thats your rule. ( good rule btw) use regular oil. its cheaper in the long run.
not saying the synthetic is bad, i just cant justify its price. even tho its dropped some in the last few years.
my brother swears by synthetic oil. he buys it in bulk on line so he gets a good break on the price. he does his oil at 5,000 miles.
we even flushed his tranny and went with a full synthetic tranny fluid. his rears also have synthetic gear oil. not sure if he did the transfer case yet. oh its a 05 yukon. so lots of fluids are needed.
