Back to the topic, I just looked at a jug of STP oil, 10W30 I think it was, and as far as origin:
"Made in the USA from domestic and imported product".
That was the dino product, black jug, not the synthetic.

I've used it in my DD & plow truck for some time, no problems.
On a race or special engine, I'll only use a name-brand performance oil.
On a couple of the FT motors using any oil with a reduced zinc & phosphorous, I'm still adding some of the old GM EOS.
Basically that decision is based on valve spring load.