Hmm,maybe I can shed some light here.
Seems the Syn manufacturers didn't used to use a lot of E/P additive on their engine oils.
They assumed that their oil was the be all,end all.
Wrong.
Most commercial syn's that I've seen are highly refined crude base stock.
Not true syn's.
They just get the syn' rating because they are so refined.
No our engines[not Porsche or Corvette] are not the stiffest blocks G/M ever produced,so unless your block is bored and honed with torque plates,I would allow a little extra leeway[breakin time].
The issue of the E/P additives was not really addressed until recently by the Syn' manufacturers.
We tested a bunch of different oils a few years back for our I/M training and guess what?
The Syn' did the worst on the test out of all the oils.
The conventional dynos lasted 1:20-1:35 before breakdown.
The syn we tested [Pennzoil,if memory serves] got to :15 seconds.
Huh!?
What happened to the syn's superiority?
A buddy of mine who was at the course a few weeks earlier said he spit on the wheel and it did better than the syn'!
Hmm.
IMO,the best thing you can do for engine break in and longevity is to run a good dino for the first couple thousand miles or so and get the "biggie" oil filter adaptor.
That's the way to fly.
JMHO.
