For the s50US engine it seems a FULL SYNTHETIC is NOT REQUIRED, but the engine does like a multi with a hot weight of at least 40.
If Mike S looks at this post, I did come across a thread regarding the flickering oil light & post/email me if you want that info. Oil pump nut & oil pickup tube stuff.
Personally, I do like synthetics or semi syn as the OC interval is a bit longer & engine internals stay cleaner.
