Not so sure about some of those figures. The S-type achieves full potential on 91 AKI octane (95 RON) so use of anything higher is a waste. Use of gas lower in octane than 91 AKI has the POTENTIAL of reducing mileage due solely to spark advance being pulled out, but I'm not sure I've seen any consistent conclusive results posted here or anywhere.

E10 does have 3-4% less energy potential of pure gas but on a car that can achieve 30 mpg on the highway best case scenario, that still only represents only 1 mpg. Very difficult to actually measure this small a variation.

All S-types were factory built to be fully compatible with E10, like all other cars of the era, so there's no need to go searching for pure gas.


Welcome to the forum and you sure picked a doozy of a topic for your first post! There's plenty of first person testimonials from owners (including myself) who have operated their S-types or other Jags with similar engines on 87 octane with no negative effects. This includes persons who used low octane for a very long term simply because they didn't know any different. I'd suggest you give it a try and see if you notice any reduction in power or mileage.

One thing sticks out- you mention an 18.9 cent difference in price between regular and super. That's got to be a typo. In looking at on line gas prices for your area, I see only a variation of 8-11 cents per litre. That would mean a difference of around 6 bucks per tank full or with 3 tanks per week, an extra $900 per year.

If it helps you feel any better, gas prices in Toronto are well below national average with $1.27/L for regular. I'm near Montreal right now and average prices are $1.41/L, more expensive than your super.

 

There is 1 gas pump that I know of in northern utah that has 100 percent gas. It also is the only 92 pump I have ever seen in Utah as most are 91. It's an hour or more drive for me. I try to get to it when I'm in the area but it's not worth it to drive down for every fill.

I thought about picking up a little ford ranger and putting one of the 50 gallon tanks that has its own powered fuel hose as my dad had one of these in his truck when he was a project superintendent for a construction co. as it worked very well. But with that amount of money I could just mix my own race gas with xylene or toluene.

I wish there was a place that carried 93 or 94 at the pump here. I have lots of friends that all have FI cars that would love to put better gas in them.

 

Well, when you decide to sell your car, be sure to quote that testimonial as part of the advertisement, so I don't buy it by mistake.

 

This is interesting considering in the northeast all premium gas is 93. Sunoco and Amoco (now BP) carry 94 as a 4th grade.

And SOME stations used to carry 85 as a "discount grade"

All our gas is E10, and also has mtbe in the winter blend

Take care,

George

 

Yup.. What he said.. Some stations in Ohio only carry 87 / and 93. The majority are 87 / 89 / 93. BTW... Take a good look at your stations fill area for their delivery... Most will only have a storage tank for 87 and 93 (regular and premium) with the mid-grade a blend of the two....

Remember folks... Like it has been discussed on here a million times.... All the different gas comes from only a couple of refineries, then it goes to a handful of distributors where it is blended with ethanol, then finally to your gas station..

Can't tell you how many times I've noticed the tanker truck making a delivery is a different company than the brand the station is selling...

 

Robin-

The usual theme of this website is 'here's your choices, use what makes you happiest'. If you're got some credible data proving that the use of regular octane or E10 gasoline causes some harm, please provide it.

If not, I'd appreciate your not posting confrontational comments inferring that I am somehow mistreating my car. If nothing else, unfounded statements on technical matters simply confuse new posters that are trying to get what should be a straightforward answer to a simple question.

Thanks.

 

Considering my brother owns a gas station that used to be my dad's. I'm slightly qualified to speak on this. Yes we have two tanks, one for 87 one for 93. Does all gas come from a couple refineries... SORT of. Yes but they run different additives and formulas depending on the purchasers. Kind of like a bakery banging out batches of cookies based on customers orders.

Now the truckers are also usually independents. SO what it says on the trailer is misleading too....


You know those mom and pop gas stations that have no brand affiliaton and gas a few cents cheaper? We'll here's what they are. They take overages. Tanker has 1500 gallons of left over exxon formula on board. He brings it to George's gas. Next tanker has 1000 of shell formula on board. In George's gas's tank it goes.... Mixed in with the exxon, and whatever else. the ONE manufaturer that doesn't do this is BP. They have a completely closed operation.

Take care,

George

 

It's simply the greedy gas stations can get away with selling 91 as premium beacuse we are so high above sea level (4400 ft give or take) so most car owners realize 91 octane is crap as most cars that are not FI run ok on it.

What's funny is we have several refineries right here in Utah so it's probably not a supply issue.

As soon as some one starts modding their FI car, it becomes clear that 91 is garbage.

 

Wait wait... 4400 feet elevation so your down like 20% on power, AND 91 octane to pull timing back? WOW. I bet an XJR feels like an XJ8 in the Rockies. No wonder all the fast cars are on the east coast....

Englishtown NJ is consistently the fastest track in the country... 27 ft above sea level.

I'm surprised Home depot can keep toulene and xylene on the shelves LOL.

Take care,

George

 

We will let the moderators and members decide what's inappropriate, Mikey.
My comment stands. If it is deemed inappropriate, I will refrain.

Other members may like to look at this:

E10 Tips - Precautions Necessary with Ethanol Gasoline Blends.

 

I'll chime in on this one only to note that you yourself have absolutely no credible data either. You've got your own personal anecdotal evidence, and that's it.

However, on the other side of the argument, we have the manufacturer's recommendation, and the opinion of a guy who worked for one of the major oil companies in some capacity as a chemist suggesting it might not be sound advice.

The issue I have with it (especially as a new guy here) is that in my opinion the "go ahead and use regular gas" avenue is the reasoning that qualifies as the "unfounded statement on technical matters" that would confuse new posters.

There is a mountain of documentation and recommendations advocating high-octane fuel only, and relatively few personal anecdotes advocating the use of regular gas.

That being said, I'm sure we all appreciate you letting us know your own (positive) experience using the regular octane gas.
The more opinions (data), the better.... and the easier it will be for forum members to make their own informed choice.



The one thing I will point out with that particular link is that it is written by / hosted on the website of a company in the business of selling fuel testers to measure the alcohol content in fuel.

I haven't researched the matter myself, so I can't comment on the substance of their article, but they do have a pretty big investment backing one particular horse in that race so some bias might be expected.

Thanks to you both for weighing in on the octane question!

If nothing else it makes for thought provoking reading.

 

ANND here we go again. I figure the Jag can run on anything you put in there, but it will not run at peak efficiency due to crappy gas. Kinda like if you tried to eat McDs then go run a marathon. You've got the fuel, but is it the right fuel?

 

You make some good points. As to when anecdotal stories become sufficient in number and depth of study that they can be accepted as credible evidence would be an interesting discussion on it's own.

Rather than trying to define that but to answer the new gentleman's question, is there anyone that has any evidence that using regular octane gas causes harm?

*edit forgot to ask- could you point me to the post about a chemist suggesting it might not be sound advice. I'd like to read up on their findings.

 

Spinall-

There's a simple reason why octane ratings of gas sold at high altitude are lower than at sea level. The air is thinner resulting in peak cylinder pressures. This means that the potential for detonation is reduced as is the requirement for octane enhancing additives.

Keep in mind that octane levels have nothing to do with gasoline 'quality', 'purity' or levels of other additives.

 

These days you can never be sure about everything you read...

My current understanding is that Canada has mandated an average of 5% ethanol in gasoline, but that at least some distributors have achieved this average by adding 10% ethanol to regular brands, and left the high-octane blends ethanol-free.

Oil refineries cannot afford to accumulate sour, high-sulphur or high-tar light oil products that are produced in small amounts from time to time when things go wrong - they either have to be re-processed or "got rid of" by blending into a finished product, as long as the finished product itself does not go off-grade as a result. Adding 200 gallons of such s**t to a tank of 200,000 gallons was not uncommon, provided the lab does before-and after tests.

But which product to add to? Not:
LPG, because it needs to readily evaporate,
Jet fuel, because it would fail critical tests and make people nervous(!),
Diesel fuel, because it would be off-grade on flash point.
Fuel Oil, because it would make it explosive.

So, guess where it goes - gasoline! But not premium, because that's the high-end part of the production line. Good old bottom-of-the-line regular. No one knows, no one minds as long as the car keeps going.

I'm sticking with premium. When I put my foot down, I don't want to have any worries of detonation, I want the Jaguar to GO.

 

It was RobinB, the other guy you were discussing this with:

 

Ah- OK. Thanks.

But there we get into anecdotal stories again plus some serious technical errors- referring to pre-ignition as being similar or related to detonation when they are completely independent and unrelated as later discussed.

RobinB spent his career in the refinery business. I spent mine at a major engine OEM in all aspects of engineering, customer support and field reliability.

If low octane gas has all sorts of bad things in it- how come we never see cars that suffer as a result?

 

"Originally Posted by Robinb
In earlier times I was chief chemist at 2 oil refineries owned by a recognized major. I know the specs of low-octane regular and high-octane premium gas, and I have seen the octane-testing engines at work in the lab."

Pardon my lazy quote process... didn't want to dig down that far....


But, please tell me, was your time as a chief chemist before or after the advent of advanced computer controls in cars?

I ask because I have also read in countless "manufacturer's instructions" that lower octane fuel can be used but will result in a reduction in performance. It says NOTHING about damage.

The real point here is not how much power a naturally aspirated V8 is making, it is will it hurt the car to run 87 octane. No, the car is smart enough to "roll things back" enough that damage won't occur.

Now the computer in my 600ES, an 80's turbo car, just controls the fuel system and some other basic things. If 87 is run in it that thing will knock and ping under even the slightest load...I know, long time ago I let a girl friend fill it up..OOPS.

Conversely, I own a handheld tuner that remaps the PCM in my 300. With the highest horsepower tune, they insist you run 93. Why? basically the lower limits are no longer there and if you run, say, 87, you will hurt the car.
BTW, this same company also makes a tune for 87 octane (the manufacturer specifies 89) that is supposed to give you better fuel economy then putting 87 in on a stock tune. I tried it, but I can't stop myself from flooring it getting on the highway so it was a waste for me. I get the best MPG out of my car running 93 along with the 93 tune....

 

If I remember correctly, I had a friend back in the 80's with a T-Bird turbo coupe and he could retard the timing if a lower grade of gasoline was used via a switch on the dash. According to my sales brochure, my Toyota Solara is actually rated at 235 hp if premium is used and only 225 if a lower octane is used. I've ran both 91 octane and 87 octane in my TL and it now has 155k problem free miles. If a car from the 80's had such technology and my current middle of the road Camry does, then why would our premium grade, technologically advanced cars not be able to adapt to regular?

FWIW, my 01 Cobra would diesel if I ran anything lower than Sunoco 94....but, that was when they still sold 94 and it was only $1.35 a gallon....

 

I think it's time for me to opt out of this discussion.

Yes, JOsworth, it was before the advent of advanced computer controls, but octane, detonation and pre-ignition were well-recognized and understood at the time.

Yes, Mikey, I do know that detonation and pre-ignition are not the same thing, but with your background I am sure you would not disagree with the comments below:

Because of the way detonation breaks down the boundary layer of protective gas surrounding components in the cylinder, these components can get very hot over sustained periods of detonation. Eventually this can lead to the far more catastrophic pre-ignition.

While it is not uncommon for an automobile engine to continue on for thousands of miles with mild detonation, preignition can destroy an engine in just a few strokes of the piston.

Due to the large variation in fuel quality, a large number of engines now adjust timing or boost pressure accordingly in order to offer improved performance on high octane fuels while reducing the risk of engine damage caused by knock while running on low octane fuels..

I am at a loss to understand the statement that octane is not related to fuel quality - octane is THE measure of quality. Within reason, everything else about gasoline IS identical.

Anyway, it was good to see everyone's opinion.