There is NO BENEFIT to running a synthetic in this application! NONE! None. You won't see longer engine life, better mileage, etc. etc. etc. etc. Stick with 15W-40 HDEO in the B & RB Mopar engines. There is zero reason to use a synthetic.
Originally Posted by 440Magnum
Not needed... they lived for decades on Group II oils before I had them, after all. But after all the work I've done and the current state of the art, they're going to get synthetics anyway. No reason not to given the infrequent changes.
Originally Posted by Rob_Roy
Any 15w-40 HDEO will work fine in that application. No need for a synthetic.