Spanish olive oil is very strictly managed with clear definitions of what extra virgin oil is as well as the other grades of olive oil. We also have quite a selection of small batch local olive oils. Some people here are as fanatic about this as wine enthusiasts.
If you can find original package Spanish olive oil you will get what it says on the bottle. When it comes to white label brands in places like the us all bets are off. In that case better stick to California olive oil.
It’s not really that simple any more. There’s a magazine in Germany called ÖkoTest and they do a lot of testing of all kind of products. We were shocked at the results for olive oil (and these were all from Europe, Italy and Spain), most of them all had mineral oils from processing probably and only one or two from the 20+ brands tested were free of mineral oils and had decent or ok overall results. Even some of the BIO/organic ones were not so good.
Italy's EVO Is already a joke currently. Most brands, even old, famous ones are re-selling oil from Spain or Greece (and sometimes even Morocco and rest of Northern Africa).
In Spain the situation is a bit better, for now, because olives are still a bit cheaper (even if last year the thing changed drastically due to draught and very bad harvesting, and prices skyrocketed like 2.5x)
As I understood the magazine article, the mineral oil could come from a couple of sources, including for example harvesting machinery.
I wonder if seed-based oils (like rapeseed a.k.a. canola) would be better in this regard, as the seeds are maybe a bit more protected until a later stage of processing... just guessing here though. Olives seem to be a bit of an outlier because there it's also the fruit that is oily and used is used for making the oil.
Do you know by chance if ÖkoTest also did tests with other types of oils?
Edit: Just checked the recommended articles, they also tested rapeseed. TLDR; nope, not better
The tests I'm finding seem to be mostly white-label brands with who knows what kind of oil. I'm talking about single source olive oil. It's a bit more expensive but you generally get oil from small operations and co-ops that can be either eco or not.
At least the ones that claim to be 100% California have some level of the law checking on them. Everything else is a crapshoot.