If you love the cars you own, and you plan to keep your cars to 200k+ miles, then use an oil which will protect the engine the best
(which to me means a euro based oil with a HTHS >= 3.5).
One good example on Amazon in the US is the 5 quart jug of: Castrol Euro 5W-30 A3/B4 for $31
which meets Mercedes MB229.5 spec. I did a compare of MB 229.5 with API SP on the Lubrisol website:
Oils which meet MB 229.5 score a 9 on the anti-wear score on the lubrizol graph.
Oils which only meet API SP only score a 4 on the anti-wear score on the lubrizol graph.
So API SP has a really low bar for wear protection.
I'm sure 99% of the people on BITOG website will still continue to use API SP, which is fine.
But for my cars, I prefer the HTHS >= 3.5 with the European Lubrizol anti-wear rating of 9.
Any car going up hilly mountains with high RPM's and high engine heat can benefit from a higher HTHS
than the owner's manual specifies. And nearly every engine sold in the US that is speced for 16 or 20 weight oils
is speced for 30/40 weight oils in Europe, Russia, and Australia. Automakers spec the better oil in places where there are no CAFE fines
for the exact same engine.