My 2005 3.0 Jag has a manual that recommends gas at 95! Our gas stations don’t even have that high of octane. It is 91. Today I filled up with 87. It seems I heard someone talk about how gasoline mixtures have changed in recent years. What rating should I be using?

 

Hello,
what you've come across is in irritation that's been in Jaguar owner manuals for years and they seem very reluctant to correct. The gasoline specified (95) is in the RON rating systemhich we don't use in North America.

Our gasoline s here are rated in the AK I system which is relatively easy to convert from Ron. What you want is gasoline rated at 91 octane like you were previously using and is generally advertised as premium or super..

The gasolines itselvsf didn't change it was simply the rating system but this changeover was done back in the 1970s. I 've forgotten why they changed over but we're stuck with it now.

 

Probably political like you said Mikey....about that time gas prices spiked and bad things were happening at the station...the government and the oil companies got together and made the new system to validate the price i bet....you know, give the public something to simmer them down

 

Looking at the USA/Canada handbook, it says 91 AKI. It does not mention RON.

This may mean some have the wrong handbook (which is odd, but stuff happens).

It used to be possible to download one's choice of handbook and I think that is still possible.

 

Then the OP as well as myself would have the wrong manual. How strange.

 

It is but why not try downloading the right one if you want it.

In case you can see a publ #, the USA ones tend to have their first numbers 18 (the UK are 10).

 

I have a Canadian spec car which is sometimes markedly different than US spec. Usually Metric Spec vs. Imperial .My manual has an 18 series part number but aside from the octane confusion seems correct for a Canadian vehicle.

Sine the OP has not returned for a chat or god forbid a thank you,I think I've lost interest in the topic.

 

What??? I asked a simple question and got a great answer......not from you. I AM grateful for the info. My car is new for me and I have lots of questions and am not a sophisticated car person.

 

But no one else answered your original question.Good Luck!

 

Mikey did answer your question.

He explained the difference between RON and AKI fuel ratings.

In my 2005 XJR 18 series manual it states that 95 RON fuel should be used. Mikey stated that is the same as 91 Octane here in the USA:

My manual was published in May of 2004 .

 

That’s what I understood.

So now I get 26/27 mpg on the highway but pay slightly less than a dollar a gallon more than my beater Subaru that gets slightly better mileage. But the Jag is much more fun to drive!

 

Reading this thread, I'm not sure what the debate is. Here in the US, most all gas stations have 2 or 3 grades and one is marked "Premium". The owner's manual says we are supposed to use "Premium" grade fuel in our cars. I go to a pump and select "Premium" to pump.

Do other countries have more than one grade of "Premium"?

 

 

thanks for looking that up
for fun. I looked in a hard copy of the 2004 XK owners manual. I happen to have. It also specifies 95 Ron fuel for a Canadian spec car. No mention of AK I. That makes four examples right here of North American Jaguars that specify the wrong rating method of fuel. In doing a search on the site I can find dozens if not hundreds of similar questions to the OP's inquiring about what octane rating of fuel to use as the 95 fuel specified in the manual is just not available here. All of these posts were from North American owners which logically would be the only ones affected as the AKI i. Rating system is not used anywhere other other than in Canada, United States, and I think Mexico. It's more than just my imagination, that this happened and I wonder if Jaguar was printing all manuals showing only the Ron rating system and only recently switched over to a correction in the written manuals as it seems they've corrected their online electronic manuals as Jag V8 pointed out.

Maybe Jaguar got tired of my whingeing and moaning on this website and finally got around to fixing the problem. :-)

 

Deleted. I answered my own question.