Originally Posted By: d00df00d
So my car is actually a good example of this.
In the US, Mazda insists on a conventional ILSAC-rated 5W-20 and nothing else. They prohibit synthetics and semi-synthetics in the strongest terms.
In Europe, they spec ACEA A5, and have strongly recommended their own Dexelia Ultra 5W-30 -- which must be at least semi-synthetic. They also call for longer OCIs.
In Japan, it's API/ILSAC again -- but they'll often use 0W-20 synthetics, and they market their own Mazda-branded RX-8 specific 0W-30 full synthetic (PAO/ester). Various well-respected rotary tuners also market fully synthetic xW-30 and xW-40 oils specifically for rotary engines.
Australia gets to use 5W-30, but gets the same breathless prohibition of synthetic oils that the US does.
Mazda doesn't recommend ILSAC 5W-20 in Europe or ACEA A5 5W-30 in the US, even though oils like those are easily available in either market. Dexelia Ultra isn't available in the US. Their RX-8 specific 0W-30 isn't available outside of some regions in Asia.
Which one is the "real" spec?
If CAFE is the only reason for ILSAC 5W-20 in the US, why don't Europe's own fuel economy requirements, emissions requirements, and hideous fuel taxes impose a similar constraint? What's to say the European spec is better anyway? Maybe the US spec is the "real" one, and the only reason they spec a heavier ACEA A5 oil in Europe is to cope with the longer OCIs. But then why would Mazda's own tailor-made RX-8 oil be a 0W-30? For that matter, why don't they ever export that oil to Europe or the US? And why is it fully synthetic when they insist you can't even use a semi-syn in most other markets?
No one but Mazda really knows why they are doing it this way. But if you assume there is a "real" spec that one of those markets is closest to, you have to make up some crazy convoluted just-so stories to answer all the questions that come up.
If you imagine it's due to subtle differences in tune and/or significant differences in fuel composition, that's not much easier to substantiate -- but it's based on facts that are well-known and endorsed by people in the relevant industries, and it's FAR less vulnerable to Occam's Razor than all the rationalization you'd have to do otherwise.
ACEA A5 is a rough (older) equivalent to API/ILSAC oil but with tougher spec's. We don't recognize ACEA spec's here in Merica. Mazda says ONLY 5w-20 ILSAC oil in the U.S. because that is the oil that was used when they ran the EPA mileage tests and certs.
So my car is actually a good example of this.
In the US, Mazda insists on a conventional ILSAC-rated 5W-20 and nothing else. They prohibit synthetics and semi-synthetics in the strongest terms.
In Europe, they spec ACEA A5, and have strongly recommended their own Dexelia Ultra 5W-30 -- which must be at least semi-synthetic. They also call for longer OCIs.
In Japan, it's API/ILSAC again -- but they'll often use 0W-20 synthetics, and they market their own Mazda-branded RX-8 specific 0W-30 full synthetic (PAO/ester). Various well-respected rotary tuners also market fully synthetic xW-30 and xW-40 oils specifically for rotary engines.
Australia gets to use 5W-30, but gets the same breathless prohibition of synthetic oils that the US does.
Mazda doesn't recommend ILSAC 5W-20 in Europe or ACEA A5 5W-30 in the US, even though oils like those are easily available in either market. Dexelia Ultra isn't available in the US. Their RX-8 specific 0W-30 isn't available outside of some regions in Asia.
Which one is the "real" spec?
If CAFE is the only reason for ILSAC 5W-20 in the US, why don't Europe's own fuel economy requirements, emissions requirements, and hideous fuel taxes impose a similar constraint? What's to say the European spec is better anyway? Maybe the US spec is the "real" one, and the only reason they spec a heavier ACEA A5 oil in Europe is to cope with the longer OCIs. But then why would Mazda's own tailor-made RX-8 oil be a 0W-30? For that matter, why don't they ever export that oil to Europe or the US? And why is it fully synthetic when they insist you can't even use a semi-syn in most other markets?
No one but Mazda really knows why they are doing it this way. But if you assume there is a "real" spec that one of those markets is closest to, you have to make up some crazy convoluted just-so stories to answer all the questions that come up.
If you imagine it's due to subtle differences in tune and/or significant differences in fuel composition, that's not much easier to substantiate -- but it's based on facts that are well-known and endorsed by people in the relevant industries, and it's FAR less vulnerable to Occam's Razor than all the rationalization you'd have to do otherwise.
ACEA A5 is a rough (older) equivalent to API/ILSAC oil but with tougher spec's. We don't recognize ACEA spec's here in Merica. Mazda says ONLY 5w-20 ILSAC oil in the U.S. because that is the oil that was used when they ran the EPA mileage tests and certs.
