Gasoline Grade

I recently purchased a 2005 X-Type, which I absolutely love. I've been putting in the premium gas, but do I need to? If I can get away with regular unleaded, I'd prefer to.

thanks
Todd

HELLOOOO.... So just tell me what grade you all use.

Todd

Hey Todd,
1st Congrats on your purchase....I too have the 05, 3L auto and love it.
2nd.. The best fuel I found that actually saves gas is the premium fuel 91 octane or better. I've been using 93 and she just purrs like a kitten.

I think the owner’s manual also states to use 91 or better. You can by all means use the 89 but your performance and fuel economy will suffer. If you decide to use 89 you will after the second fill up notice a drastic decrease in fuel economy (due to the computer advancing the timing to max) and sluggish performance.. (Been there, done that)

Anyway, good luck..

Thanks Racer - The good stuff it is for my new baby (man I love that car...)

Yeah, shes something else....love mine too....wish she had a turbo now......h,mmmmmm

May be strange but I've recently been using regular grade (89) and have found the mileage improved! (3 liter) Probably some decrease in performance, but an acceptable trade-off under most conditions.
Bart Kinlein

Todd,
First, I suppose it all depends on where you live. Northwest states where you're 1K or better feet above see level or south east right at see level? At Higher altitude, lower octane will do.

Here is jersey, I used to use the 89 and the performance was horrible....then I read the owners manual, clearly states using 93 or better for my 3L. Once I started using the high octane fuel, not only did I get the performance, but fuel economy jumped as well.

The computer compensates for your low octane fuel, and remembers you have a high compression engine, 10.5:1. That is the same compression that race engines use.....but since your computer "retards" the ignition to compensate, you don't hear the pinging going on in your engine, as it starts to tear the engine apart. Keep using that fuel and you'll see a decrease in fuel economy, since the computer "retarded" your ignition, your performance level dropped considerably as well. If you're a slow driver and don't care about performance....you probably won't notice the performance loss....but I can guarantee that your fuel economy will start to decrease.

My suggestion and experience is to stick with the high octane. I don't like paying the high prices as well, but that’s what my baby needs...

My local dealer (Troy Michigan) informed me that they recommend 89 Octane during the winter months.

I'm undecided on this, and would welcome any thoughts. In theory, during the cold months, the density of air is higher and so more Oxygen is sucked into the engine. This would imply a higher Octane grade is necessary to take advantage of this and avoid knock. I'm not sure what other additives are used during the winter which may counteract this tendancy. Obviously the engine computer is monitoring the incoming air and compensates for the pressure and temperature, and as stated before, the knock sensor is altering the ignition timing to eliminate knock.

The cheapest and crappiest grade of fuel that you can get in Europe is 91 Octane, although this is now very rare, as those people who tended to buy such fuel have all migrated over to Diesel because of the better fuel economy. In the UK you cannot buy 91 Octane, the lowest grade is 95 (premium is 98). That is why the owners manual with your car references 95 and 98 Octane.

So I imagine that Jaguar, Land Rover and Ford have to buy 91 Octane specially for their testing facilities. All calibrations are normally done using 91 Octane as the baseline fuel for engine development. I'm not sure how Jaguar would mimic 87 or 89 grade without getting it made specially.

So - any comments on the winter fuel recommendation?

Hmmm, never heard of that before..That’s a new one. I do know that they manufacture a different fuel for winter months..Less oxygenated I think. No sure.

Last winter I accidentally put 89 in it (the pump guy didn't hear me I guess and it was too late to do anything about it) saved 5 bucks I think. Anyway, long story short.....never again! lol

I suppose you can try it out for a test and see what you think...all depends on your driving style I suppose. I'm more aggressive and need that extra punch, but if you're a slow and easy...I suppose 89 wouldn't hurt for a short term anyway...

Gasoline octane is a common question and the recommendation from the manufacturer is usually recommended. But what is the trade-off? I have used 89 on my 25L, 03 SPORT since new and runs great and the odd time I did use higher octane have not noticed a difference in mileage, nor performance. The car adjusts itself. Porsche and Mercedes engineers have admitted that all cars are made to run on ANY octane because in many places in the world only one octane is available. So you will only trade off a little of mileage and performance according to the engineers that designed the engines. It will not harm the car. I do know oil companies make a fortune on higher grade....

I don't agree....yes, cars will run on any grade....that's becasue the computer adjust the timing and such..trade off is....carbon build up, engine damage do to sever pining (you won't hear it, ping sensor adjust) poor fuel economy and poor performace.

If you read your owners manual, it states that for best performace, fuel milage and perventive maintenace, for the Jag, use 92 or better...the higher compression engine needs it. Your actually wasting money by using the lower octane fuel.......


But hey, if it works it works..

I know I have been through this with people back and forth. The reality is in many places where high performance cars are sold there is only 1 octane rating and that is why they have variable octane knock sensors. But it get too emotional for many people to think that their baby can run on cheap gas. I am only saying you will not destroy your car.

Octane is the most important issue when it comes to selecting the proper gasoline. Octane is a numerical rating that indicates a fuel’s resistance to detonation. The higher the octane number, the more resistant it is to detonation. Higher octane allows an engine-builder to create higher cylinder pressures to make more power. If your engine does not detonate, rattle, or ping on 87-octane fuel, there is no advantage to using a higher-octane fuel. Also, a common fallacy is that higher-octane gasoline burns faster or slower. As octane increases, the components that increase the octane chemically react in the combustion process to merely prevent detonation rather than change the burn rate.

Gasoline Octane Facts



Printable Content

When you pull into a gas station to fill your car's tank, you almost always have a choice of several kinds of gasoline. The majority of pumps usually offer a product called regular; other pumps are labeled premium, super, or something similar, and their product sells at a price about 12 to 13 percent higher than the price of regular. The difference in name and price is based on the gasoline's octane, with regular gasoline having an octane of at least 87 and the premium or super fuels having an octane ranging from 89 to 95.

What is octane?
Octane actually has two definitions.

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One is chemical: Octane is a flammable hydrocarbon liquid that along with other hydrocarbons -- pentane, hexane, heptane, and many others -- is refined from crude oil and makes up the blend of chemical components called gasoline.
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A second definition: Octane is a measure of a fuel's tendency to knock or ping when it is mixed with air and burned in the cylinder of an engine. This octane rating is not based on the amount of chemical octane in the gasoline. It is called octane because pure hydrocarbon octane is used as a knock standard, with a rating of 100. Gasoline, made from a blend of octane and other hydrocarbons, may have a higher or lower rating, depending on its tendency to knock.


How is octane rating determined?
Gasoline is subjected to two testing methods to establish its octane rating: one, called the motor method, runs the gasoline in an engine under load; and a second, the research method, runs the gasoline in a free running engine. The research method gives slightly higher ratings, and the octane number displayed on the pumps is an average of the two methods.

Octane facts

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Knock occurs when cylinder pressures are high. It is normal for an engine to ping a little at full throttle because cylinder pressures are very high at full throttle. Engine knock, however, should not be ignored since it can result in serious damage to the engine.
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High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when cylinder pressures are high.
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If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in switching to higher octane gasoline.
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If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could be a problem with the car's ignition timing or exhaust gas recirculation. On high mileage engines, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.
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Many of today's new cars have fuel-injected engines that need, at least periodically, to use gasoline with a detergent additive. They do not need high octane gasoline unless the auto manufacturer recommends it. Some gas stations, however, have detergent only in their high octane gasoline. If this is the only way you can get a detergent additive, you may want to buy high octane gas occasionally.
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Always follow the auto manufacturer's recommendations in your owner's manual.

Octane myths
High octane gasoline improves mileage.
In general, if your car is designed to run on 87 octane gasoline, high octane gasoline will not improve mileage. If switching to high octane gasoline does improve mileage, you might find that a tune-up will give you the same improvement on 87 octane gasoline.

High octane gasoline gives quicker starting.
No, it doesn't.

High octane gasoline increases power.
If your car is designed to run on 87 octane gasoline, you shouldn't notice any more power on high octane gasoline. Again, if it does make a noticeable difference, you may need a tune-up.

High octane gasoline has been refined more -- it is just a better product.
Additional refining steps are used to increase the octane; however, these additional steps do not make the gasoline any cleaner or better. They just yield a different blend of hydrocarbons that burn more slowly. The additional steps also increase the price.

Thanks.....if you can use any grade gasoline other than the minimum required, would you subsistue your oil for something less than required? I don't think so.

Nuff said.

peace.

See, that's why it gets emotional...... use what you want as far as octane is concerned. We went through the same emotion on another car site I belong to. Just knowing what octane is designed for (higher compression motors for performance) yet the Jag is 10:1 which is right in the middle. But if you sleep better with higher octane. Go for it. Oil? I use synthetic since new.

ok..ok...you use synthetic...I use Castrol GTX and primum fuel.

all good...

Fuel octane affects engines quite a bit actually. I had a 96 honda 900rr crotch rocket and could definetely tell the difference between lower octanes and higher octanes. They suggested using 91 and higher in the bike and you can totally tell the difference in fuels. The amount of performance lost to using lower grade fuels is detrimental to motorcycles. You may not realize these things in a car as they weigh 3000-5000 pounds vs. my bike with wet weight barely tips over 400lbs. wet (wet meaning with all fluids.) You flick the throttle on that bike and you notice hesitation, inconsistencies, and lack of overall performance! You may not notice these in a heavy car as they don't react half as fast as cars. Personally I'll stick to using whatever the manufacturer suggests. My sister has a lincoln mark VII with a high perfomance 5.0 and if she doesn't put premium fuel in it the car knocks! We believe (mechanics as well) that the previous owner used low-grade fuel in the car which resulted in the knocking of the engine. In every dohc that I have heard of except for some 4-bangers premium fuel is recommended. Thats just me though, after riding my bike and noticing such a tremendous difference I'll stick to the recommendation of the people making the bike. I also noticed the difference between the 110 leaded (TURBO BLUE) fuel I put in the bike vs. 93! That thing purred like a freakin' lion-no joke! I also find that the smell was much better than the regular 93 fuel that didn't smell very good on the non-cat bike!

Amen brother..There's a reason why they have the higer octane fuel...If all cars took the same type fuel...we would only have one to choose from.

good info again...

A couple of points:

A 96 fireblade has carburettors the a cable throttle control, and therefore the fuelling control is significantly different to the Jag engine which has multipoint fuel infection and drive by wire. However I agree with the comment about fuel grade affecting the bike; the power to weight ratio is so different the difference will be stark.

Being European, I couldn't believe that the lowest octane grade (95 RON) was higher than the highest US grade; engineered down to a price I suppose.... Hence my comments previously about what Jaguar would use to calibrate their engines in the first place - 91 RON, which is the common minimum grade available.

To my knowledge no testing was done by Ford in the USA, the engine was wholly designed by Jaguar in Whitley. Also at that time Ford were wedded to the use of their in-house EEC5 engine control module (now a Visteon offering), whereas Jaguar were standardising on Denso as their electronics provider. This would mimimise the amount that calibrations and control strategies could have been transferred between the two, and therefore any US based testing on Ford vehicles would have had limited use. On the basis of this I wouldn't go below 91 RON as it is unlikely to have been validated below this level.

I'd still like an opinion on why my Jaguar dealer would recommend 89 Octane for the winter here in Detroit.

I don't care if its carbs or fuel injected to me the bike had older technology which shouldn't have made quite a big difference with the bike not having the technology fuel injected engines have these days. My feeling is that if the bike can react like this on a bike why wouldn't it matter in a fuel injected computer monitored car. I just feel that in a car thats 10 times heavier you won't notice the difference quite like I could on my bike which was much lighter. I am convinced that if 91 is recommended on that thats what I'm going to do as well as in this car. I'd get it in writing from the dealer (jag of troy I assume) that they say its good to do that and when something happens blame it on them. Maybe they know a thing or two about these scammer gas stations who change the amount of water they add to their gas-had it happen before here in Michigan :)

Not trying to start a fight or anything just trying to give my 2cents!

Well let me try to explain although I am no expert. We have here temperature ranges from 100+F in the summer to -40F in the winter. We have a few fuel companies selling winter gas. Basically it's a gas and ethanol mix that promotes cleaner burn, reduces carbon monoxide and is usually sold in the winter months because cold engines operate less efficiently and produce more carbon monoxide. I notice no difference in power or consumption when I come across this fuel but I do notice a different smell... not anything big but just different. I guess because it burns hotter and the air outside is cold.

Cheers,

As for a good read on gas...

http://new.api.org/aboutoilgas/gasoline/gasoline-octane.cfm

I don't know why the Jag dealer would tell you to use 89 in your neck of the woods....doesn't sound right....maybe he was just trying to be nice and save you a few bucks.....??

1. Good advise from a non gasoline expert..........sweeet
2. You taking it and pocketing the few cents you saved.......even sweeeter
3. The look on your face after your engine destroys itself......Priceless!

Just messing.....You seem to have all the facts (according to your posts) so why do you think you can use 89?

Personally, just last night, the wife and I took an 8 hour drive to Pennsylvania....(nice long quality time with the wife.) Anyway, filled up with 94, I normally use 93, and one word...WOW....

The car was performing sweeet....every time....acceleration was wow...noticeable wow! Filled up 3x last night with it...awesome...and at 2.49 it isn't cheap I suppose compared to my normal 2.29 but well worth the extra fun! The exhaust even made a differnt tone..according to the wife...she wanted to know if i did anything....now that's noticable boys..when the wife asks that question...you know you're not imagining it...

Road trip.

I'm glad that you enjoyed the quality time with your wife. I'm just waiting for the kids to clear off so that we can do the same (several years yet I suspect....).

94 Octane

Now you can understand why I am so frustrated with the fuel over here (the US), when I'm used to buying 95 Octane at my local garage, supermarket or wherever and can get 98 Octane for a small amount extra. Mind you I'm not frustrated about the price (in Holland its currently Euro 1.30 a liter which is roughly $6.50 a US gallon).

89 Octane

I agree with your comments, I don't trust the advice at the moment. I know I'm safe with 91, but I'm new to (a) the extreme cold in the winter (b) the idea of radically different winter fuel (c) fuel of such a quality it gums up your motorbike carburettors during winter storage.

However - there's a clue in the recent reply - ethanol. I will investigate further (ethanol has significantly different combustion properties).

Cheers, Graham

OH GOD DON"T DO IT! Ethanol is cheap (poor gas mileage, poor performance, and over all crappy, compared to gasoline...plus side it's cheap...I guess people feel better spending 1.29 a gallon) and your engine\fuel system has to be capable in supporting the ethanol fuel. I don't think Jag is in anyway capable of running with that fuel.

As for high fuel costs...I lived in Italy for 4 years, paying 4 dollars per gallon, when it was 99 cents here!! The good part was that they (Italians) only offer one grade of fuel!

I personally think you'll be fine with 91 octane....

There is no way around the fuel cost problem...well yes there is. Park your car and walk or ride your bicycle or take public transportation.

Unless we all unite (like in the 70's) and stop buying gas for just on one day (the same day across the states) will we be heard. Right now the gas companies don't feel the pain....record profits in the billions...people driving huge SUVS with monster v-8's to the local store....are not sending the right message...nobody is complaining......we are all paying the price they want us to pay.....

Anyway...don't wanna get too far off here...but I'm sure you know what the heck i mean...

Don't worry I don't necessarily want to use ethanol (I've had experience in engineering for the Brazilian market, I know what flex fuels can do). But if the oil companies are reformulating their fuels for the winter with ethanol, I want to research it and work out what that means.

Ethanol may also explain the comment earlier about gas stations putting water in the fuel - the two are so miscible that it is impossible to eliminate water from ethanol (from memory, pure research grade ethanol is only about 96% pure).

I'm sure that the Jaguar engine is flex fuel compatible; the manual says up to 10%.

Anyway, I'm off to sample some ethanol soon at the hotel. Cheers!