Re-read post #5, last sentence.

 

If a heavy `spark knock' is detected even when using fuel of the recommended octane rating, or if you hear steady `spark knock' while holding a steady speed on level roads consult a Jaguar Retailer to have the problem corrected.

I read it to mean that if you use 91 or better and it still knocks, take it to the dealer, it's broken.

 

Hey Big Mike! What does that myth have to do with my suggestion of using STP in reality? I simply suggested using STP if your using mid grade gas, to help clean out the injectors and what not

 

http://www.torcousa.com/torco_product/un_acce.html

 

...your a genius Mafiosooooooooooooooo, lolz

 

Thats what was in the tank when I murdered the cats poured the full bottle to 1/4 tank of Shell 93 octane. trying to keep 12.5afr

came close on one pull of 12

 

LOLzzzzz...wtf! no wonder those cats blew up on ya! Those additives are notorious for doing more bad than good if not measured properly before adding

 

its ok I hold myself responsible, not the cats fault. They were aged and low use.

 

well i found out what was going on i made the mistake of not checking the air filter since service records show the oil and tires rotated religiously on the mark by a local shop. turns out the filter was from 06 and hadnt been replaced in 60k miles. now hopefully i wont be spending as much but, there still hasnt been a clear answer here. For people like me who dont drive far enough to get the engine really toasty is it possible that running mid grade would be safe and efficient in a s type v8.

 

I don't think you're going to get a more definitive answer beyond what's already been said.

If you're driving 100 miles and using $50-60 worth of gas, there's something very wrong with your engine. Cheaper gas won't fix that problem.

 

sedakai - What mpg are you actually getting?

 

Regardless of octane rating, all high quality gasolines already have detergents to keep fuel injectors and other components clean. By using additives like STP, you'd be doing nothing at best.

On occasion, I've seen dirty fuel injectors. It's usually on cars with well over 100,000 miles on them. Using a high quality fuel injector cleaner that's administered through the shraeder valve at the fuel rail is the only real way you might be able to clean deposits without a bench cleaning. A little STP won't do anything to injector build ups.

 

You're right, but it seems to help the tin foil hat brigade feel better about themselves.

 

I'm not trying to put anybody down. Fuel injector cleaners, and other additives are marketed as the genuine deal. Unfortunately, there is no real way for the average car owner to objectively analyze benefits of using most additives. Lots of people just want to make sure they're taking good care of their car so they can do their best to avoid major break downs, if possible.

Here in the Twin Cities of Minnesota, gas prices are as follows:
$2.70/gallon Regular
$2.80/gallon Super
$2.90/gallon Premium

Running super will save $0.10/gallon. STP Fuel Injector Cleaner = $6.00. You'll need to run through 60 gallons of fuel (1,200+ miles per week or 60,000 miles per year) just to break even... and that's if the method was valid, which it's obviously not.

Don't believe in the hype about octane boosters, either. At most you'll see a jump of 1-2 octane at a cost of $5.00, and you need to add that to every tank, lol. So while stepping up 1 grade costs you about 10 cents per gallon at the pump, it costs you 30 times more by using an "octane booster."

 

Sorry, I meant (3 times more) not 30, haha.

 

To be honest with you, I use Lucas fuel injection cleaner, and hands down that shiat makes a world of a difference on any old car not only cleaning but in the MPG! I deal with a lot cars not just mine but others and I always recommend LUCAS products and at the end I just hear nothing but gratitude

 

Note that the octane boosters give you 0.1 increase, not 1.0. Gotta read the bottle reaaaaaaaaaaal carefully to see that.

 

Looks like our brothers with X types enjoy going in circles too

https://www.jaguarforums.com/forum/s...ad.php?t=45374

 

Mikey, I was giving them the benefit of the doubt based on some online testing I found. Results of octane boosters will vary based on brand and the amount of fuel the booster is used to treat. In the testing done by Europeancarweb, the results were generally in the 1 octane range (10pts, lol)

http://www.europeancarweb.com/tech/0...ted/index.html

jag89 I'm skeptical any additive could make a significant impact to fuel economy. 15 gallons of fuel is 1,920oz. A 16oz fuel additive makes up only about 0.83% of the volume of fuel in the tank, and that's not enough to do anything to the hydrocarbon content of the fuel or improve the combustion efficiency for that matter. If the additive was able to break down carbon deposits on the spark plug or cylinder heads, it might improve valve seating which would improve compression and fuel efficiency.

That said, if you want to remove carbon deposits on an engine, warm the engine up, grab yourself a spray bottle of water, and spray a steady mist of water down the carburetor while the engine is running (I'm dead serious). The liquid water will turn into steam and remove carbon deposits on the inside of the engine. Spraying water is a heck of a lot cheaper than fuel treatment products, and it'll work better too.

 

Hi,
I just love the price of your fuel, think I'll move to the USA if you would have us that is
For 1 ltr of 95 octane rated we are paying £1.15 to £1.19 which = £5.41 per Imperial gallon. Higher octane @98 rating is 4/5pence a litre more.
So from a UK perspective your fuel is dirt cheap. Shhhhhhhhh say no more. At the moment the exchange rate is £1.00 = $1.60 so gives you some idea on the cost of our fuel. I believe the US gallon is a little less than the imperial measure, so that should be taken into account.
Just to let you see how the other half live, or don't live come to that.
Regards,
Inver.