What's going to happen now? Thrown rods? Will the engine fall out?!

The sad thing is I only use up maybe one tank a month so I probably won't be able to drive the car very hard until I use up all this substandard gas!

 

Modern engines compensate for lower octane gas by automatically retarding the timing which results in less power, lower gas mileage, but no pinging either. If it were me, I would not drive aggressively, and when the level gets down below 3/4 start adding 93 octane to dilute the lower octane.

 

yep, plus 1

nothing will happen, just drive like you wife would for the next half a tank..

 

OH MY GOD! HOLY CRAP! Your tires are going to fall off and the rotator shift knob is going to turn into a red reject button! LOL


Actually nothing is going to happen to damage your engine. The ethanol content will be higher than 91 octane premium which your engine will adjust to automatically. No worries.

 

Is there not an octane additive?

This would solve your problem. http://www.lucasoil.com/products/dis...id=50&loc=show

 

I cannot believe that anything will happen to the cars engine. Here in the State of New Mexico our fuel stations don't even offer a 93 octane gas. It's either 86 or 91....no other choices. I use the 91 and found no reported problems.

The issue of gas octane levels has always been a topic of controversay. When racing formula race cars, many competitors would use high octane race fuels while others would use pump gas. I have been told that the lower octane fuel burns better. So I don't really know what is best, but would have to assume that Jaguar would not build an engine that only burns a specific octane fuel.

I am sure all of our cars have a suggested range of octane to be used.

There are many websites that discuss the octane of gasoline:

Octane Rating, Best Gas for your Car, and other Gasoline Facts | Exxon

Which Gasoline Should You Buy - Gasoline Chemistry

HowStuffWorks "Is premium gasoline really better for luxury vehicles?"

It might help taking a few minutes to read some of this info.

 

Maybe I'll just siphon the gas out into a lesser car--my wife's Hyundai Sonata.

This is my first forced induction car (I've had 10 cars to date) so I didn't know if they were more sensitive to low octane gas. I imagine they are, but not enough to become a real issue just once!

 

They usually are as the static compression is much higher. But, if you drive easy, you will be fine.

Use up half the tank and refill with 93. You will be good to go.

 

Use to live in a country with similar problem (Lithuania).
But I always compensated with octane booster (BMW M5)...
Someting I too would use if my XKR was driven on 91 octane.

 

The ECMs knock sensor will detect if there is any pre ignition, and retard the engine timing accordingly. You should have nothing to worry about but top off with some 93 octane when the fuel level drops just for piece of mind.

 

Myths about Octane boosters....check this out!


Interesting......

 

well, I can say as much as higher oktane will give you more HP, if you have a prefomance car such as ours are..



and oktane booster eleminated engine knocking in my VW 16V as well as my Honda 350XL, and definatey made my M5 care preform better...

however.... in the US and north America, you oktane is messured differently than here in Europe.. So I guess you do not need booster or higher oktane than 91

From the web
"Well just curious do tell what kind of car you have after I answer. I may follow up. Well RON (research octane number) is really the European way for fuel classification for octane numbers and doesnt apply to the (R+M)/2 we have in the US. If your manual says to use 98ron this implies a 91 to 93 octane rating in the USA. "

 

Seriously the best thing you could do is to burn a gallon running errands and then stick in a gallon 100 octane... if you're worried about it. It's not the end of the world and likely you'll notice very little difference with normal driving but if it were me I'd look for some high octane crack juice to supplement the watery stuff in your tank now.

 

Any opinion on running lower octane gasoline in higher elevations? I live at 5700 ft. My Acura MDX has always used 87 octane even though 91 is recommended. Never have experienced a problem in that vehicle running lower octane fuel. It was my understanding that in higher elevations you lower the compression ratio in the engine and have less need for high octane.

 

From the 4.2 workshop manual:

98 RON = 90.5 octane. 91 RON = 87 octane. So the car is set by default to use 91 octane, but will adjust to 87. I run my 5.0 XKR on UK standard 95 RON (89 octane) unless I'm going for a speed run or track day, when I use 98 RON.

 

From what I have read the only impact will be on HP and mileage. A few years back I bought a Lexus with a 272HP V6 . The OM said to use premium gas which I did . I also knew that modern engines had sufficient electronics to adjust to various fuel octanes but I went along with the manual. I then traded it in for a later model with the same engine and it recommended regular fuel but rated the engine at 268HP. There was no difference in the performance even though the cars were 3 years apart. My bet is there would be no noticeable difference in using reg vs premium gas. The interesting issue here would be what gas mileage he is getting .

 

Found an interesting writeup about octane, compression levels and more here:

Car Bible Fuel Engine

It also had this graph for octane/elevation

 

You could drive the next mile like this to drain the regular fuel:

 

Sorry to disagree, but that article is one of the worst I've seen on the subject. The author is confused about even the most fundamental concepts.

Beware anyone that uses the terms 'detonation' and 'pre-ignition' interchangeably. They are each very different phenomena unrelated to each other. More importantly, octane ratings have NOTHING to do with how quickly the fuel burns. This is one of the oldest myths and misunderstandings around- it just won't go away and is perpetuated by articles such as in the link .

Pre-ignition is NOT spontaneous combustion nor is it an explosion- it is normal burning (deflagration) of the fuel, ignited prematurely by a source other than at the desired location and the desired time at the spark plug. Increased octane rating of a fuel will not cure pre-igtnion nor will reduced octane levels induce it.

Detonation is as the name says- the fuel detonates (explodes) rather than burns. The sudden and intense release of energy is what causes the 'pinging' noise and is what can destroy an engine in mere minutes of left unchecked. The most common cause of detonation is overly advanced ignition timing accompanied by low octane ratings of the fuel. This sets the stage for an abnormal combustion event where the fuel either detonates of it's own accord prior to the spark attempting to initiate combustion, or immediately following the spark, but at another spot in the combustion chamber.

In any case the shock waves caused by the explosion, either singular or in some cases multiple, are what separate 'pre-ignition' from 'detonation'.

Increasing the octane rating of the fuel simply lessens it's tendency to spontaneously combust and nothing more.

The common misconception is the high octane fuel 'burns slower' which is completely inaccurate. If one has an understanding of how detonation or pinging actually occurs, it is obvious that the speed at which a fuel burns would not cure or prevent the event.

I had to stop reading the author's wild misconceptions when he got to compression ratios. According to him, we should all be using fuels somewhere in the 97-99 RON or 93-95 AKI octane range.

Jaguar's own recommendation is 95 RON or 91 AKI.

Sorry for the soap box, but this general subject is one of my pet peeves. Since all modern Jags require higher octane level fuels, the subject of 'what if I use regular' comes up frequently for a variety or reasons.

In tracking the comments posters have left over the years, other than a few sporadic reports of check engine lights on a handful of X-types, no Jag seems to be affected by usage of low octane fuel either by audible noise (pining), reduced power levels or increased fuel consumption.

Seems our beauties are not temperamental beasts when it comes to meal time.