I always put premium (93 octane) gas into my XJ8, but is it absolutely necessary? Just curious.

Also, the nozzle that sprays windshield cleaning fluid broke off my wiper. Is this something I can order a part for and fix, or should I just take it to my local guy? If it's an easy snap-on kind of thing, I'll do it!

Thanks in advance for your help!!!!

D.J.

 

As to your first question, what octane number do you refer to? AKI, RON or some other. My manual states 91 AKI octane is recommended. Where did you get the idea 93 octane might be "absolutely necessary".
Guess you didn't see the "grade of gas" thread?
As to the washer nozzle, I would say that depends on your mechanical aptitude and patience.

 

I run 89 in my 2002 XJ8, never heard a ping or felt it pull timing.

 

How about your XJR??? heh, heh

 

Welcome to the forum -- you'll find that asking about premium gas opens a real can of worms and sparks some interesting discussion, mostly from those who apparently know a ton more about the issue than the average bear!

As for the part you're looking for, you'll find a lot of sources if you just do a google search for the part, and then ask members of the forum if they think it's a good deal, etc.

Good luck!

 

91+ water/meth +7 octane from Torco Accellerator

jet fuel basically

15 psi normally, 17 if the temp is below 70 degrees

 

I always ran 93 as specified in the Owners Manual until a few years ago there was a gas shortage in the southeast and only 89 was available for about three weeks. So I used 89 octane.

Nothing different. Same MPG, same acceleration, same everything. The knock sensors will retard the spark if you exceed the knock limits of the 89 at 500 times per second. Admittedly, you will not be able to achieve the published horsepower using the 89 octane because of the knock sensors but I never asked the car to produce its maximum HP anyway.

Used 89 ever since.

Let the debate begin . . . . . again.

 

Man, I don't know where you guys are getting the 93 octane from the owners manual. My MY 02 and my MY 99 XJR manuals both say 91 octane AKI. So does the MY 2000 manual.

Here is a link for the MY 2000 Vehicle care Manual:

https://www.jaguarforums.com/forum/a...e-handbook-pdf

Look on page 6-9- it seems pretty unambiguous to me, but so many folks keep babel-ling about 93 octane that there must be some ambiguity somewhere!

 

Ross, I have to believe the 93 figure is popping in because there are a number of locations where 93 AKI is marketed as premium fuel. Most of the stations near me in the Shenandoah Valley have 91 AKI as premium, but a few have 93 AKI listed on their pumps. People tend to remember "premium" and whatever octane number they see on the pump at their "usual gas stations."

You are indeed correct about the figures in the 1999 Vehicle Care Manual. It reads, and I quote:
Use only Premium Unleaded gasoline with a minimum Anti-Knock Index (AKI) of 91.

Oxygenated gasoline blended with ethanol (max 10%) methanol (max 5%), or methyl tertiary butyl ether (MTBE) (max 15%) may be used. Reformulated Gasoline with a minimum AKI of 91 may also be used.

It is recommended that only fuels containing detergent additives are used in your vehicle.

 

Well, I admit my mental health is subject to question, but I have looked and never found any reference to any octane other that 91 AKI, but 93 octane keeps coming up! I am experimenting with AKI 89 right now in several of the Jags I drive, but my wife will not allow it in her MY '02!

 

Oh Boy..I was going to leave this alone!
My jaguar manual: (Australia)
"Use unleaded fuel with an OCTANE rating of at least 95 RON"
(Research Octane Number)

And that is what I use. I haven't experimented with a lower grade of fuel because of the small amount of extra cost between grades.
A Wiper arm should be available on eBay if you are willing to use a second hand one. Easy enough to replace.

 

95 ron = 91 aki.

 

Welcome to the forum delfinparis,

The fuel required depends on where in the World you are. Jaguar vehicle specifications vary for different markets and particularly the engine mappings are set to be suitable for fuel availability in the country in which the vehicle is sold.

When you get a minute, please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

Fuel requirements are covered in the Vehicle Care Handbook. These are different publications and content for different markets as can be seen from the two examples for 1999MY below for US and RoW.

Fuel requirements for US market vehicle specification is Premium Unleaded with a minimum AKI (Anti Knock Index) of 91:



(click on the image to enlarge it)

The recommendation for UK market specification is Standard 95 RON.

Fuel requirements for ROW (Rest of World) acknowledge consistent fuel grade is not always available:



(click on the image to enlarge it)

Jaguar certainly make clear the possibility of damage from using low octane fuel.

Graham

 

RON (Research Octane Rating)
MON (Motor Octane Rating)

AKI (RON+MON/2)

Wikipedia does a decent job in explaining the octane rating systems.

In discussions here and elsewhere, even when a given participant has specified the measurement system being used, there invariably seem to be disagreements due to lack of understanding of the rough "translations" from one system to another.

What I find curious is that it seems that RON and AKI are incredibly common "on the pump" octane ratings used, depending on your location in the world. Does anyone know of anywhere where MON is the number on display? It seems that MON numbers don't often enter any of these discussions and I presume that's probably because they just don't show up on fuel pumps or in owner's manuals. I'd be curious if there are niche markets in which MON is "the number."

 

Can't say that I've ever heard of that. Perhaps it's just as well as there's enough confusion already.

 

I doubt the engine mapping is really different for different countries. It is the octane measurement used in a specific local that varies and the manual references that. But that is just my conjecture. I would love to see contrary data!