I did some more research and of course this car requires premium fuel, which I already knew that. Yet, I find that usual posts say that 92-95 octane is optimal with low ethanol.

Now there is lies the problem. Most places that I even remotely know of usually have the up to 10-15% ethanol sticker on it. And here, 91 is highest to be found and probably not very good quality. The Chevrons are always out of and been out straight for the past 5 months at least. There is one Shell somewhere across the town but 91 also. The rest is basic hole in the wall stations, although the Circle K created no problems unlike many of the 7/11 station's gas.

I think I remember seeing 93 in Atlanta (1441 miles away from here). But where in the heezies is one to find low or better, no ethanol gas these days? I wonder if this gas thing is one of the reasons why Americans have many runing issues with the cars.
When I was in Germany, many of them was a little shocked at the amount of problems the American MBZ/BMWs had reported.

 

When I was in Wisconsin last month, 93 was easy to find. I only went to one station that only had 91. On the way to and from Wisconsin (from Florida), every station that I stopped at had 93. In Florida, 93 is easy to find -- seems like they all have it.

As for the 10% ethanol -- I haven't even been looking at those signs on the pumps, but now I will. I thought they all had the 10% sign, never seen one saying it had more than that.

My brother has to use an additive for his outboard motor on his boat because of the ethanol (I believe). Is that something we should be doing with our cars?

 

The specification for 92-95 octane gas is the UK/European measuring system, commonly called 'RON' or research octane number. Gas in North America uses a different rating system called 'AKI' or anti knock index.

92-95 RON gas is equivalent to 87-91 AKI, so using 91 is on the upper end of what's required. Using anything higher (92-93AKI) is a complete waste of money.

No gasoline presently being retailed here has higher than 10% ethanol. There are no drawbacks to using E10 other than an very minor loss of mileage or power than most drivers don't notice. E10 is a bad non-solution to energy problems motivated purely by politics, but it doesn't destroy cars are per internet legends.

There is no need or benefits to additives- most are snake oil.

 

Are you saying that we should be using regular unleaded (87) in the U.S. since that's the bottom of the range and acceptable?

 

I don't have an owners manual for your car. What does it say specifically? If the range in the manual is truly 92-95 RON then yes, 87 would be acceptable.

BTW- the octane rating has NOTHING to do with 'quality' of the gas or the quantity of additives in it. It's purely the resistance to detonation, and nothing else.

 

IMO 87 AKI is below the 92-95 RON requirement. It would be better to be above the requirement than below it as the quality of fuel detetiorates with age, is also affected by temperature (both the temperature of the day and the questionable temperatures that some of our Jaguars can get to) and of course the original quality of the fuel itself.
I run my XJ6 3.2 on 95 RON and my others on 98 RON (except for my sportwagon on 91 RON) and these higher octane fuels also have more 'cleaning' qualities than the lower 91 RON that we have here.
If you are in doubt there are octane boosters available and while some have been tested and have shown no improvement there are some that have increased the octane number under test. I'm sure google would bring these tests up.

 

If the OP has doubts about using 87 AKI being adequate or equivalent to 92 RON (please supply a reference if you have one), it would be much simpler to switch to 89 which is available everywhere in N. Am.

It's never cost effective to use little bottles of booster, even the ones that are not snake oil. Most advertise an increase of '1 point' in octane rating- what they mean is raising gas from 87.0 to 87.1, not to 88 as is commonly assumed.

 

How can it be an opinion? AKI and RON have a numerical relationship. Any particular number in one system is either equivalent or not equivalent to some other number in the other system.

Ummm....no. Shell USA supervising chemist.

 

So we could run US 89 octane in these cars and we're in the clear? I thought it was premium 91-93 octane only. I've yet to find 93 octane since moving out west from New England.

 

I believe the manual/vehicle care handbook says 91 AKI minimum. Which means to me that 91 is fine. No need to go searching for 93 if 91 is all that's around, in my opinion.

 

Somebody please go RTFM and tell us what it says.

 

Hey, you're the one who said the 92-95 was RON, without any documentation -- I think that's what lead the discussion down the "so I only need 87" path.

The 2000 XJ vehicle care handbook that I have on my iPad says on page 6-9 (hopefully this is enough RTFM for you! LOL):

Fuel Requirements

Use only Premium Unleaded gasoline with a minimum Anti-Knock Index (AKI) of 91.

Oxygenated gasoline blended with ethanol (max. 10%) methanol (max 10%) or methyl tertiary butyl ether (MTBE) (max. 15%) may be used.

Reformulated Gasoline with a minimum AKI of 91 may also be used

The use of high quality fuel containing ‘intake system deposit control' detergent and other additives will help to keep the vehicle's intake system free of deposits and its fuel system free of corrosion and gumming.

If high quality fuels containing ‘intake system deposit control' detergent and other additives are used continuously, there should be no need to add any after market products to the fuel tank.

If problems are experienced with starting, rough idling or hesitation when the engine is cold, it may be caused by gasoline with a low volatility. Try a different grade and/or brand of fuel. If the condition persists, see a Jaguar Dealer or a qualified service technician.

Oxygenated gasoline

Fuels that are blended with compounds containing oxygen, called oxygenates, may be used. Common oxygenates are ethanol or grain alcohol (blended at no more than 10%), methanol or wood alcohol (blended at no more than 5% with necessary co-solvents and additives, and MTBE or methyl tertiary butyl ether (blended at no more than 15%). The type of oxygenate may be found on the fuel pump or by asking the attendant. In certain areas of the country, oxygenates are required to be in all fuels to help improve air quality.

Generally, difficulty should not be experienced while operating the vehicle on fuels containing oxygenates. If problems are experienced switch to a fuel with a different type of oxygenate, or switch to a fuel that does not contain oxygenates, if available.

Reformulated gasoline

Several petroleum companies have announced the availability of reformulated fuels.

These fuels are specially designed to further reduce vehicle emissions.

Jaguar fully supports all efforts to protect and maintain ambient air quality, and encourage the use of reformulated gasoline, where available.

 

Thanks- that solves that. The mention of 92-95 octane in the OP's post might have been from the European version of the manual. My S-type, delivered new in Canada where the measurement system is AKI only specifies 95 octane RON leading to all sorts of confusion by owners not familiar with the difference.

 

Also MTBE or methyl tertiary butyl ether was mandated out of gasoline in the US and replaced with ethanol.

 

so basically 91 will do.

Yeah I know different brands have different qualities or else three cars in a row would not have problems from one location (all require premium). I guess the quality in some places affects the detonation? As one car I had in the past that required midgrade (88-89) had not so much noticable problem but then again it was a "normal" run of the mill american car (3.5 v6 Chry. 300) compared to the other three being euros that are known to be a little skittish and sensative to fuel and probably designed more for the euro quality found in the likes of Germany (the 560SEL ran noticable better after a tank of gas over there and german mechanic said america was known to have only so-so passable gas, not the worst but not the best.)

I've seen signs of 15% ethanol out here but when I spot that sign even if it says "up to 15%" I drive off rather facing running out of gas than fill up with that stuff.
With the Jag and most modern cars I have yet to experience much problems with ethanol but with the euros from the 80s in my stable some dont seem to like it too much, especially the rubber components of the system (since upgraded with ethanol compatable parts but it was a pain in the butt). The BMW didnt seem to give a crap as it was only the "low end" non-performance oriented 528e. I think I probably could pour that watered down crap they serve on the military post gas station down the tank and it woudnt make a fuss. With the Jag, the cpu probably will compensate and the MBZ of 88, forget about it.

 

I wonder where the mechanic got the idea that gas here was inferior to gas in Europe? That's similar to a mechanic here having an idea that gas over there is better worse (pssst- it's not!). Same-same.

 

Kinda doubt it.

Since the mid 1990s we have only had two choices: 95 or 98 RON at the pumps.

But at least we know what we get. (should do, we have $11/gal).

AKI for you is what to look at.

To the OP, putting higher than recommended will make no difference to performance, but will make a difference to your wallet.

Providing, you have stable quality in your outlets.

 

I have been using 87 octane in my 1998 XJ8 for several years with no problem. No detonation or loss of power.

 

more than likely. Probably more to do with brand than anything.

 

at this price, ten cents extra or so is miniscule. About an extra dollar every ten gallons seeing the choices as 87 88 and 91, with premium recommended I never tried or even thought of trying to put lower in the Jag. Probably wont make much difference but in the older cars, the difference is noticable and with the 300 putting in regular made no running difference persay but it did tend to suck down the less than recommended a lot faster which basically nullified any savings if not cost more per tank. Given that the mbz is 88 and made a difference with grade and the 300 was 06 with no running difference but burnt more with lesser grade than book recommendation, I figure the Jag might be in between; little difference in performance but slightly less mpg which would nullify the ten cents a gallon savings anyways. Fro mwhat I gather from the responses and the recommended fuel, I dont think it is possible here to find higher than recommended grade fuel. Maybe when I travel cross country but to think of it, usually places with 93 dont have 91 along my route (west to east 120 odd miles of I10 and about 1300 miles of I20.