A problem with injectors or plugs....such as clogging or plug deposits? If your injectors clog or the plugs have deposit build-up, it *won't* be a result of lower *octane rating*.

That's as solid of an answer as *I* can muster. Maybe others can do better.

Such problems would likely be the result of *not* using a Top Tier gasoline. Top Tier gasolines meet specific standards of quality, detergent content, etc....none of which have anything to do with *octane rating*.

It's entirely possible to buy a higher octane fuel which doesn't meet the Top Tier quality standards and equally possible to buy a lower octane fuel that does meet the Top Tier quality standards....so don't be fooled by octane numbers alone.

Since you've experimented and found that a mid-range octane works well for you then sticking with a Top Tier gasoline should assuage your worries.

Cheers
DD

 

WHAT FUN!

Octane tells us what the resistence to ignition due to the heat of compression is. If you run a compression test on non-supercharged engines and you have 160 PSI or less, you can run regular gas. If you are above 160 up to 180 PSI then you need premium.

Retarding the spark works on knocking due to the mixture burning too fast. However it won't stop pre-ignition. To do that on engines with varible cam timing, the intake valve closing gets retarded and closes further past Bottom Dead Center into the compression stroke. That drops your dynamic compression ratio on down. Depending on the amount of available cam timing, the dynamic ratio may drop on down to 7 to 1 or less.

The reason that we are seeing the high compression ratios is that small combustion chambers resist knocking and they run more efficently. Advancing the cam timing gives better gas milage and more torque down low.

Holy pistons are not good.

 

Jaguar bothered to spell out in detail in the handbook what fuel to use and why. So, hoping that the PCM will compensate (whether by VCT or anything else) outside the specified parameters looks...... overly optimistic. But you never know till you try it and maybe break it!

For the OP's car, reckon the potential damage would be more than the car is worth?

 

[quote=Mikey;331099]What's that got to do with anything?

Oh- you didn't bother reading a page or so of replies. Never mind. [/quote

Jaguar is notorious for wasting your money by overcharging for simple service. personally im starting to think the difference between 87 and 91 is like splitting hairs. I stopped bothering because its all so opinionated, i haven't seen one post, that is backed by fact, saying running mid grade will do harm to your engine.

 

Face it, you say you haven't bothered doing the reading and you've got strong, apparently somewhat outrageous, opinions so do as you will. Thankfully I will never be buying a car from you!

 

Agreed. Kinda rude of the OP to ask a question and not bother reading what respondents have to say.

 

Actually there have been many intelligent posts on both sides, many backed by facts or personal observation. Just run 87 and be done with it.

For the others, are there any other car manufacturers that recommend 87 octane in their turbocharged or supercharged engines? I really don't think Jaguar is alone in their 91 recommendations.

 

This is a Fig Newton of dreamland:

 

++

 

Thanks for a great thread guys! I always enjoy reading the lively debates on here - it's what makes this a great forum. I have and always will run what Jaguar recommends for my car (that being said then, I know a few of you might be willing to buy a car from me in the future...)

Really, what the issue is, is the cost of fuel - which will always cause people to ask if it's ok to run the lower octane fuel. Hence our lively debate. Because really, if higher octane gas were cheap, we wouldnt need to ask these questions. Maybe we should be debating with the government all of their taxes they place on fuel. I know we here in Canada are taxed to death. But alas, no government will be pulling their fuel taxes anytime soon, so we're back to square one - expensive gas.

We drive kick a$$ cars. Let's put kick a$$ fuel in them and get every ounce out of them we can. That's why I bought mine - didn't you?

 

tried to be nice but why dont you stop flaming my thread troll?

 

thats not what i said maybe you should read a little deeper into my posts as they have obviously misunderstood i stopped reading all of the posts like v8 that amount to jaguar says so lets blindly throw money out

 

That piece about John Dinkel ends on a funny note.

Max horsepower doesn't come from running the highest octane gas that you can find. It comes from running the lowest octane gas that doesn't detonate in your cylinders. If it detonates, you may wind up with a hole in a piston before the race is over.

 

And in this case Jag say minimum of 95 RON.

 

Wow! Ask people's opinion on fuel, get a lot of response, and then accuse one of the more avid contributors a troll?

The majority of people on here are just drivers and enthusiasts. Not auto manufacturers. What people were giving you are their preferences based on personal experience. So, basically you posted up a question then get angry with those that disagree. Not a cool way to treat people that you may need their help in the future. Again, just my opinion, so maybe I'm a troll as well.

I think the overwhelming opinion on here is.... Lower octane gas may not hurt your engine but there is just as little scientific proof. So, really just use what you want.

Again, I chose to follow the manufacturer's recommended fuel requirements. It seems to me that any time I've deviated from them or used low quality (cheap) fuel there has been a service issue. I'm one of those people that live on a real tight budget, so, if it isn't covered by a warranty, I fix it myself. So, based on failed cats, bad EGR systems, dirty intakes, fouled plugs, I find the few pennies saved by deviating from those specs does not pay in the long run...And, no sorry, I don't have a scientific report to back it up...Just lower car repair bills....

K, I'm done....

 

I run 93 Octane in ALL my vehicles, even the 2010 Camaro V6, reason is because on that one, I added a custom exhauset, X-pype all the way to the rear, with adding a Performance Programer. I have found that using this gas eliminates, many mechanical and service issues with all my cars, because of that I'm always gonna stay with the higher grade Fuel. Vehicles Run better with it.

 

I give up too..............

 

Use whatever you like. You'll be more satisfied with your choice.

 

My ex has a Chrysler Crossfire (Mercedes drive train, normaly aspirated) and it specifies 91 or higher. Also, the R isn't alone in requireing premium. Our 3.0 also requires it...according to Jaguar

 

Such as...... ?


Cheers
DD