I've been a life-long Pennzoil guy and have typically ended up running their conventional high-mileage oils since I hold onto vehicles for YEARS.
Last oil change I looked and looked for conventional high mileage 10W-30 and noticed fewer, if any, options. Even
@Jerry Bransford's recommendation of NAPA's conventional high-mileage was a bust.
Like
@tr21triton says, Pennzoil's website mentions their conventional high-mileage is a blend. Wilder still, they show even their
conventional oil is a blend. I'm no chemist and don't work in Pennzoil's formulation lab, so I don't know what constitutes their non-synthetic to synthetic "blend" ratios. I'd imagine anything with an additive could/might/maybe be called a blend.
When I went in person to my O'Reilly's and looked at the labels, I didn't see the term
conventional anywhere on the front of the Pennzoil High-Mileage bottles. The rear label doesn't say anything about its makeup other than its additives making it able to condition seals. That's a sample of one store, but I'm somewhat suspect of what they mean when they sell it as "conventional". If they mean the oil is blended at 51% regular to 49% synthetic making it "conventional", that's a little crazy to me.
Having said all that, I have a hunch that all the oil dropped off for recycling when people do oil changes gets put back into the supply chain. That may be where the majority of "blends" come from, as impurities may be filtered out but synthetics can't be separated from conventional oils. Like I said, not sure on this but just a theory. Cheaper for the company to clean and reuse oils than buy pure oil and formulate it from scratch? Again, don't know.
Now, ordering from Amazon, you may be getting some old stock, non-synthetic blended, oil. Maybe their description doesn't match the product you get. Not sure.
In my case I think I ended up using the Pennzoil High-Mileage anyway, just because, and have been fine to this point.