[newpassatman]

Here is Nebraska most of our 89 octane has Ethanol in it.. Does that make a difference in how things run? Anyone know?

My 08 calls for 91 octane and I read that some people threw CEL's when they used less octane but most here say it is fine. I might have to try it, I am with the others that say screw big oil.

 

[GALVANIZEDYANKEE]

Most US gasoline contains <10% Ethanol. The exception being marine gasoline. It was found that the Ethanol ate through fiberglass fuel tanks on some old boats.

 

[barchiola]

is it the case that some cars will be fine with regular and others (even though they're the same) won't? i'm pretty set on a used Passat at this point ('07 to '09 probably) with the 2.0T and I have to admit I'll try regular in it. The '00 Volvo we had for a short time was very much unable to run on regular.

 

[Steve in Chicago]

Basically, one gallon of 87 octane and one gallon of 93 octane fuel contain the same amount of heat energy.

But the amount of energy your engine is capable of extracting from that gallon and putting to practical use may not be the same (efficiency). Back in the mechanical distributor days we would run timing as advanced as we could (just shy of hitting pre-ignition). This provided more responsive power and better mileage. Today's digitally controlled ignition systems with knock sensor feedback do that tuning for you on the fly. Higher octane fuel allows the system to run more advanced timing.

Each case will be different and depend on many factors. To know how your specific car and driving style stacks up you'd need to keep mileage logs and see what the results show. What works best mid-winter may not work as well during 90ºF summer temps.

 

[Skipsb6]

For a couple of years my money was tight so I ran the 89 octane instead of the 91/93. While I did not experience any spark knock, I
Did find that my performance and MPG was down. The past year I have been running thev91/93 octane, and my MPG is
Better by about 4MPG, and the overall performance is better. Oh, this is on my 07 with 75,000 miles on it

 

[Scottie Passatie]

I wont run 89 octane cause there is no such thing really. The tanker trucks only carry 87 and 91 octane.To get 89 they blend the 87 and 91 right there, probably as you are pumping it I would imagine. I run 91 octane in my 99 V6 and average 24.7 mgg with about equal city/highway driving.

 

[newpassatman]

I wont run 89 octane cause there is no such thing really. The tanker trucks only carry 87 and 91 octane.To get 89 they blend the 87 and 91 right there, probably as you are pumping it I would imagine. I run 91 octane in my 99 V6 and average 24.7 mgg with about equal city/highway driving.

You just said yourself to get 89 octane they blend 87 and 91. The results of that are 89, correct? Just because they don't deliver 89 doesn't make it any less 89.

47 states have some form of a fuel quality program to monitor fuel octane, the 3 that do not are Pennsylvania, Utah & Alaska.

At least that is what I have read.

 

[TC-12]

...and we wonder why ExxonMobil's 2005 profit was $36 Billion.

IMO, unless you are experiencing a detonation problem with the reduced octane, high-test is a waste of money; having 2,000,000 car owners unnecessarily spend another $100/year for premium gas puts another $200,000,000 in the oil companies' pockets. If you think your car is "benefitting" from this, fine with me.

This does a good job of explaining ExxonMobil's benefit -- and motivation -- for seeing a "Premium Gas" label on the filler cap. But Exxon doesn't engineer or sell these cars -- VW does. And to put that "Premium Gas" label on the filler cap is a DETRIMENT to VW's marketing efforts, because your local VW salesman will have to spill the beans at some point during your test drive, "Gas? You'll need to use premium." And that's a good motivator for you to walk away and buy a Nissan Maxima from the dealer across the street. (A random choice -- I have no idea what gas the Maxima uses.) So VW wants to AVOID that "premium" sticker, and yet, they put it there, an act that can only HURT their sales of Passats.

I won't argue for or against premium gas in these cars since I haven't had mine long enough to know all the pro's and con's. But I couldn't help but notice this thread began with "A salesman said it's OK to use regular gas..." Assuming this refers to a VW salesman, some of them (just like any salespeople) are as mechanically inclined as my dog. I'd love to see some knowledgeable responses here from engineer types, highly experienced tuners, or career VW/Audi mechanics, folks like that. I have yet to see in this thread any solid explanation as to how ignoring the “premium” label for years on end is not only a penalty-free decision, but a no-brainer one as well.

 

[NEWMAN'SOWN]

This does a good job of explaining ExxonMobil's benefit -- and motivation -- for seeing a "Premium Gas" label on the filler cap. But Exxon doesn't engineer or sell these cars -- VW does. And to put that "Premium Gas" label on the filler cap is a DETRIMENT to VW's marketing efforts, because your local VW salesman will have to spill the beans at some point during your test drive, "Gas? You'll need to use premium." And that's a good motivator for you to walk away and buy a Nissan Maxima from the dealer across the street. (A random choice -- I have no idea what gas the Maxima uses.) So VW wants to AVOID that "premium" sticker, and yet, they put it there, an act that can only HURT their sales of Passats.

I won't argue for or against premium gas in these cars since I haven't had mine long enough to know all the pro's and con's. But I couldn't help but notice this thread began with "A salesman said it's OK to use regular gas..." Assuming this refers to a VW salesman, some of them (just like any salespeople) are as mechanically inclined as my dog. I'd love to see some knowledgeable responses here from engineer types, highly experienced tuners, or career VW/Audi mechanics, folks like that. I have yet to see in this thread any solid explanation as to how ignoring the “premium” label for years on end is not only a penalty-free decision, but a no-brainer one as well.

I agree with you, but do you realize you are responding to posts made more than half a decade ago?

 

[TC-12]

"I agree with you, but do you realize you are responding to posts made more than half a decade ago?"

I talk to ghosts all the time. And dogs. Cats too.

There's a good chance that some of the previous posters may actually be dead by now. About half the posts above were from the last week or so, so I figured what the heck...