What countries would we be talking about in an English language manual other than the USA or Canada?
Mexico 🇲🇽 according to the manual.
Probably the reason is the high cost of synthetic oil there. Therefore, they recommend conventional oil (5W-30).
This is what I’ve been told in the past by a contact of mine. Economical reasons and availability in many other countries. It’s just not PC for corporations to come out and say.
That's exactly how it is!
Someone did a Walmart oil survey in Mexico a while back. It turns out true dino Group I oils are still the most popular oils there. They have phased out true dino Group I oils in the US a long time ago.
You can make PCMO (not HDEO) 15W-40, 20W-50, and 25W-50 from Group I base oil. That's because you can satisfy the CCS (cold-cranking viscosity) of these viscosity grades at the API's 15% upper Noack limit with a Group I base oil. You would need Group II for a HDEO 15W-40 though because of the 13% Noack limit for an HDEO.
These are the oil prices in Mexico:
Group I (15W, 20W, and 25W base oils and PCMO only)
Super Tech 25W-50 Group I dino: 43 ₱
Super Tech 20W-50 Group I dino: 49 ₱
Super Tech 15W-40 Group I dino PCMO (not HDEO): 49 ₱
Castrol Magnetec 20W-50 Group I dino: 49 ₱
Group II (minimally required for 5W base oils)
Mobil Super 5W-30 Group II: 95 ₱
Castrol GTX 20W-50 Group II: 99 ₱
Group III (minimally required for 0W base oils)
Mobil 1 5W-30 Group III synthetic: 209 ₱
You get the picture. Most people there use thick Group I oils, which is half the price of conventional Group II oils sold in US. If they upgrade to a conventional Group II 5W-30, which cannot be Group I because the base oil is too thin to satisfy the 15% Noack limit, they pay twice the money, which is already a luxury. If they upgraded to a synthetic such as a 0W-20, they would have to pay four times the money, and they don't do that. That's exactly why the Mazda manual doesn't bother recommending 0W-20 for Mexico because it's not practical for economic reasons.Cancun, Mexico Walmart oil selection and prices