Was wondering if anybody is NOT using Premium fuel in their Jaguar? I have tried it and the engine appears to run just fine, I assume the computer can change the timing for the lower octane.

 

There’s a difference between running fine and have maximum performance.

Z

 

I totally, understand that! I know it will run it's best with the higher octane, but I am not racing my cat, I'm just cruising along

 

Hello,
At 87 octane, the ignition is adjusted. This is controlled by the ECU, otherwise the engine would break down. This also happens at low revs and when accelerating. As a result, the engine requires more petrol. Is the cheaper 87 octane petrol worth it?
Best regards, Willi

 

I would characterize that as just limping along.

Just because you can survive eating dry dog food doesn’t mean it’s the thing to do. I had a friend that devised an Economic Class project on the premise that he could live for a month eating solely dry Purima Dog Chow. Thereby spending very little $$$.. He followed thru with it. But the unintended consequences were brutal on his digestive system.

That boy stunk.

Don't feed your cat dog food…… it will get even with you .

Z

 

I alternate between mid and high at fill up. Engine Masters on the motor trend channel did a series of dyno runs using the full range of fuels and found essentially no difference in power with any fuel, including 100 octane, except e85 increased power by a few%.

A former member living in North Georgia said he used 87 octane in his XK8 with no problems.

 

Well, the price of 87 octane and 91 is exactly $1.00 more, SO, I guess what I need to do is run a tank of each and see how much better my gas mileage is with premium versus "old el cheapo" 87.

 

hmm, food for thought!! pun intended.

 

Like I said, I have been running 87 and notice no difference, but I will see what kind of mileage I get with 91 versus 87.

 

On pretty much all of the forums I have been on related to cars that I have owned, there will almost always be someone who eventually posts something like ". .. can I use regular instead of premium in my xxxx. . . " Ironically I have seen these questions pop up on Corvette forums as well as other "performance vehicle" forums. I always go through the same "analysis" in terms of what the extra cost would be over the period of a year and I am sure one of my old old posts discuss this. But I think it comes out to something like equivalent to a Starbuck's or two each week so why be overly concerned about the incremental cost if you went the extra distance to get a performance vehicle to begin with?

 

I suppose sometimes people live where buying higher octane fuel is not easy, i.e. cost may not really be the issue.

(Here, 98RON & 99RON are fairly common but the car doesn't need them.)

 

Look at this price differential. 92-93 is usually about 60 cents more than 87 in my area.

 

is there a point here that I’m missing ?

Your car makes more power on the higher octane fuel. Acceleration and power is reduced with the low octane pig sweat via retarded ignition timing, etc.

Is that what you want ?

if so why are you driving an XK8 / XKR in the first place ???

Z

 

No problems ? What he really means is no enjoyment. Other than being a
poser.

an experienced dyno operator can get any result he is aiming for. Expecting objectivity from an entertainment TV show is truly laughable. Engine Masters, among others in the “info-tainment” industry choose a desired outcome. Then design a show to produce the desired result. That’s not a new concept. It’s been the de rigueur in television since its inception. Anyone remember the fixed game show scandals ?

It’s basic automotive engineering : an engine makes more power if you can advance the timing more. And you can’t do that without burning a higher octane fuel.

if a person just wants to drive around posing in a great looking car with the least possible expense for fuel, just say so, and that’s your goal and that you use 87 fuel to accomplish that goal. Thats an honest outlook.


But if you want to experience the car in a more visceral way with spirited driving, bouncing the tach needle off of the red line, you are going to consider 91 or 93 octane the price of admission. And gladly pay the piper.

Z

 

I was using grocery store gas for a while because I could get points and get a discount on gasoline. I would regularly get a P0191 (fuel pressure out of range). I searched around on here and it looked like it was due to a return valve or pressure release valve on the fuel pump and some Techron cleared it up. But for a while now I've been using Exxon high-detergent fuel with Synergy, or some such name and I believe it helps. It does cost more (93 octane always) but I'm deathly afraid of fuel pump problems. Knock on (or touch) wood, it's still going strong after 20 years.

 

I am knocking on the same wood. My 2 fuel pumps are the originals. Hope my daily driving the car and periodic use of Techron will keep them going for 20+ more years.

Z

 

Okay here we go again one more time. Assume you drive 10,000 miles a year which is probably more than most here put on their vehicles. And say you get 15 miles per gallon. Then that equates to 667 gallons of gas per year. But round this up to 700 gallons. Then if going to premium costs 60 cents more per gallon (I don't believe it is that much in my area but let's use that number anyway) we are talking about $420 more per year or about $8 per week. Like I said comes to about 2 Starbucks per week.

 

"Like I said comes to about 2 Starbucks per week......"

Starbucks ? Ha ! I'd rather spend that money on good gas - otherwise we are both drinking junk

 

You misunderstood the reason for my post. I was highlighting the $1.63/gallon price difference between 87 and 93. I only use 92 or 93 in all three cars.

 

I don't think many people use "premium" anymore. They're all putting 87 octane stuff in their white SUVs. Sometimes I worry the 93 octane stuff might get old before they sell it !