Originally Posted By: Audioquest
My understanding is that all OW20 oil is synthetic.
That's almost true, mostly. Honda branded and ACDelco are blends, maybe others. Walmart's 0w-20s are all full synthetics. No biggie.
Originally Posted By: Audioquest
Why would they recommend a mineral 5W30 as the substitute? Personally, I couldn't care less as it is leased and I only plan to do the minimum recommended maintenance, but if I can use dino 5W30, I'm using it.
For a lease for sure, buy the cheapest SN 5w-30, fine there. It's CAFE fuel economy official ratings requirements that cause Nissan to be schizophrenic about viscosities. Since MPG figures are based on use of 0w-20 (and the thinnest they could find, likely...), they are forced to put that "recommended" language in their owner's manuals.
As many have said, about any engine I've ever heard of will be just fine if not better (anti wear) if you go from a 20 oil to a 30 oil. Small increase in viscosity is alright.