which 91 octane is better on our jag engines or is it all preference?

 

Preference. Part of it also comes down to the detergent package that the local area has based on local laws. That can play a small part in which is better. Not familiar with what the laws are in Nevada.

I say run 3 tanks of 1 and then run another 3 tanks in the other and see if you can spot a difference in how the car runs and how the mileage is. Please make sure to take into account how you are driving as one can get horrible mileage compared to the other if one was done with mainly in town driving when the other was done with mainly highway driving. Put them on even footing and go from there.

I like to periodically switch between name brands as their detergent packages are different and if you are getting build up with one, when you switch to the other, it will tend to clean up what the other missed. It only takes a tank say every oil change to keep things as good as you can maintain them.

 

Shell is pretty good all around, but there is a Citgo distributor in my area that moves some 0%-ethanol to different stations. In PA, it is not legal to sell the non-alky, but some shops do...

Ten minutes into a tank, my MIL light goes out, ans stays out until I put something else in (the Citgo stations are not convenient to me)...and my mileage goes up 12-15%.

Presently, I'll be putting new sensor in all around, which will fix that issue, but the Jag does not like even 10% ethanol.

There is a bill that just went into committee here to rescind that damn law. Gasoline is cheaper, burns cleaner, and is better for the car...

 

I realize your question was comparing Shell to Chevron, but I thought it would be helpful to make mention that Costco Gas is a pretty good bet as well. All gasoline in the US has to meet minimum EPA requirements and Top Tier is 3 times the minimum required - I believe. In my area Chevron and Shell are usually the more expensive stations whereas Arco is typically the least expensive. Shell and Chevron mix their detergents into their fuel at the refinery and the added cost for the detergent mixture is passed down to the consumer at the pump.

Costco did a study, much like they do with everything, as well as extensive engine tests over a period of time, to determine what amount of detergent was most beneficial for an engine to remain clean and maintain its optimal operation. What they discovered was that 5 times the requirement was the optimal and ideal amount for Top Tier fuel. More was a waste and less didn't optimize how clean the engine would be over time and use.

Costco purchases their fuel from many distributors (again these distributors have added the minimum EPA required additives) and then Costco adds their own mixture of additional detergents on site as the fuel is pumped into the holding tanks. It would be more expensive for Costco to have their detergents mixed into the fuel prior to delivery which would translate to an increase in cost at the pump. Instead they create a type of bidding war from fuel providers to drive down the cost to the lowest price they can. They add their detergents onsite and minimally markup the cost. All this allows them to create a competitive market by managing the price consumers have to pay for gas at local stations, as well as rewarding their members with lower priced gas with the added value of more detergents to keep their engines running clean. So not only are you getting gas at a lower price per gallon, but you are also getting a better value in a higher quality gas.

 

I was also wondering about ethanol free gas. I have a few Go-Gas stations where I live and they offer 93 Ethanol Free gas, its a little more expensive but I was wondering if my Jag would run better on it?

 

Chevron is the maker of Tekron. If that is an additive they put in their fuel, it is a good thing. That cleans the stuff in the intake and on top of the intake valves real nice. I think you can also buy the Tekron by itself at like Autozone or Advanced......Be cool....Mike

 

Yes, Chevron has Tekron in it. My old Honda S2000 preferred that fuel over any other I tried. However the local station stopped pumping premium so I can't try it in The Jag.

 

Using fuel with higher octane rating than required is a waste of money. There is typically is 3-4% loss of mileage when using E10, so factor that in the cost when buying ethanol free fuel.

 

Thanks, its hard to find 91 here, its either 89 or 93. will 91 work ok?

 

I'm not using shell anymore.

 

For the best performance you can get out of our little engines, the manual says use 91 octane or better. With a higher octane, our high compression engines will run a more advanced timing. If you don't use premium fuel, you won't hear any detonation, but that is because the knock sensors have retarded the timing, as much as 20 degrees, so you won't get any detonation. Low octane means lower power. Most cars aren't running 10.5 to 1 compression, so they will run on anything short of mule ****. Our cars require it, according to the manual. Do an experiment, and run your tank almost dry. Fill the car with a low alcohol premium and I will bet you feel the difference. If paying the extra scratch worries you, you will also get an increase in mileage, though not as much to make up for how they are raping us at the gas stations for premium......My lecture for today.....

By the way, when I was working for Porsche Audi VW, we found that doctors and lawyers, who could afford the high line cars were usually the ones who tried to get by with the lowest price fuel they could find, and then complaining about the performance of their cars. I would usually just change out their AC plugs, that Jimmy the mechanic down the street put in, added a bottle of techron, and a bottle of 104 octane boost to at least get them in the ball park of 91 octane. $70 in parts and expendables and depending on the car an hour to two hours of my time, and they were happy. I also gave them a warning that cheap plugs and gas will bring them right back to me, in a month. Skip a lunch every tankful, and you have paid for your 91 octane.....Be cool.....Mike

 

While the 93 is more than the vehicle needs, it would be worth it to me to run fuel that is alcohol-free. Aside from better mileage running pure gasoline, I'm old-school when it comes to trying to avoid premature failure of seals from the alcohol.

 

I've been using E10 for over 20 years in any and all of my vehicles. Never once have I had any mechanical problems due to the fuel nor do I know of anyone who has.

The fear of E10 is way overblown.

 

i run the cheapest gas i can find ,my cat keeps purring, 87 octane
for me,im not a sucker for the pump ,