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What Octane Do You Use?

18K views 29 replies 18 participants last post by  TC-12  
#1 ·
Salesman in AUS TX :whistle: says it's OK to use regular, 87-89 octane. Performance suffers a little but no harm to the engine & almost no one uses premium.

What do you Passat owners in the real world use?

Thx, P
 
#2 ·
pdewey said:
Salesman in AUS TX :whistle: says it's OK to use regular, 87-89 octane. Performance suffers a little but no harm to the engine & almost no one uses premium.

What do you Passat owners in the real world use?

Thx, P
he is right about 89 not 87 but i always use 91 or better.
do a search "octane"
there are 100's of posts about this.
its really pennies on the dollar so use the good stuff.
 
#3 ·
I have three vehicles all requiring premium fuel including a 2000 Passat V6. About 2 years ago I switched from premium (92 octane) to regular (87 octane). All three vehicles have knock sensors which means the spark is retarded using the 87 octane vs the 92. Theoretically, this will decrease power and fuel mileage somewhat. I rigorously keep track of my MPG on each car. I can not say that I notice any decrease in MPG. This may simply be because I moved about that time and driving conditions are somewhat different. But on the same long trips, I still get about the same MPG (might vary +- 1/2 MPG on cars that average about 28 MPG on long trips. Although its hard to determine, I do believe that I did notice a slight loss in performance on hard acceleration.

Bottom line for me is I can live with a slight loss in acceleration for the $300 savings in annual fuel cost on my 3 cars.
 
#4 ·
From the beginning, I've use 89 in my '03 GLX 4Motion without any problems in performance or gas mileage. I will be doing the same with my 3.6L 4Motion; I don't anticipate having to worry about a slight "loss of performance" with 280 HP, but I'll be watching for any hint of spark knock.
 
#7 ·
my car/s(any of them...except my 2.0 gls 1996 jetta and i ran midgrade 89 on that one)) only touch 93.0 octane (Texas)..or premium wherever.
I am a firm believer in that the higher octane will yield better gas mileage offsetting the cost difference per gallon from the lower octane gas....

i have owned my passat 22,000 and have never run other than 93 ...

the a4 also runs on 93.0 and occasionally (every other month or so) i will add 2-3 gallons of 109 oxygenated, unleaded fuel.(expensive but GREAT stuff..better than any octane booster or fuel injector cleaner..)

amen
 
#8 ·
wickedgti said:
my car/s(any of them...except my 2.0 gls 1996 jetta and i ran midgrade 89 on that one)) only touch 93.0 octane (Texas)..or premium wherever.
I am a firm believer in that the higher octane will yield better gas mileage offsetting the cost difference per gallon from the lower octane gas....

i have owned my passat 22,000 and have never run other than 93 ...

the a4 also runs on 93.0 and occasionally (every other month or so) i will add 2-3 gallons of 109 oxygenated, unleaded fuel.(expensive but GREAT stuff..better than any octane booster or fuel injector cleaner..)

amen
...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.
 
#28 ·
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.
 
#9 ·
GreggD said:
...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.
hmm yah i would much rather run 87 in my passat....:rolleyes:

then your statement would include running 87 octane on a k04 audi with a giac chip with the 91 octane program..right?..b/c it is a waste of money....crap even with 89..you may not experience detonation.but doesnt necessarily warrant using lower octane fuel...

what put 36 billion dollar profit in EMB account was the fact that they jack up prices (across the board) 1500% from their cost of processing crude oil...let just face it..it is inflated across the board....

but to say that 87 or 93 is the same thing (unless you are having detonation problems)....and is a waste of money....is ridiculous.

edit: you probably fall into the same category as those that "dont want to spend the extra 2.00 bucks per gallon" of synthetic motor oil and believe it is the same as regular motor oil...just to save a buck!...sweet very sweet..
 
#11 ·
Jeez! My earliest response in this Thread was regarding my use of 89 vs 91-92; I've put 55,000 miles on my GLX 2.8 with no problems at all. I do think that Big Oil's "sales job" on the unnecessary use of premium gas for cars that trully don't need it is obvious; check out the FTC's website on this issue. However, that's not the same as advocating the use of 87 in lieu of 93. Even if the engine could "compensate" for such a loss in octane, performance and mpg would probably suffer noticeably.

PS: I AM a synthetic oil fan.
 
#12 ·
wickedgti said:
... I am a firm believer in that the higher octane will yield better gas mileage offsetting the cost difference per gallon from the lower octane gas....
amen
Basically, one gallon of 87 octane and one gallon of 93 octane fuel contain the same amount of heat energy. The benefit of higher octane fuel is a slower combustion of the fuel. Thus, on the compression stoke there is less chance for predetonation (fuel ignites before the spark) as the fuel / air mixture compresses. It's this predetonation that results in the knocking or pinging sound. When the air/fuel mixture is compressed heat is generated. Higher compression engines are more likely to predenotate (knock) on lower octane fuel everything else be the same. For example, diesel engines (high compression) use no spark plugs to ignite the fuel. They rely on the heat developed during compression. Cars equiped with knock sensor will adjust the timing if knock is detected so that there is less chance of predetonation. Thus, any difference as far as MPG will be negligible and won't justify the higher cost of premium fuel. Higher octane fuel, if no knock, is a waste of money. IMO, buy the lowest octane fuel that allows the car to run "knock free".
 
#24 ·
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 90ÂşF summer temps.
 
#19 ·
Why buy a Turbo car that is made to run its best on high octain gas, and then get petty about spending more for gas? Do the figuring. Hi test runs 20 to 30 cents more per gallon than regular. Consider my B6
2.0 L turbo adverages 24MPG (conservatively) combined driving. If you drive 15000 miles a year you will use 625 gallons of gas. 625 X .25 = $156.25. For $156 more a year make mine hi test.
 
#20 ·
there are people in this world that don't deserve that $156.25 any more than the rest of the money I spend on gas so I'd rather keep my petroleum based fuels purchases to a minimum. I'm also considering a new Ford Focus and a new Jetta TDI wagon. I've been having a heck of a time finding a car I can use for my business that gets good gas mileage and is affordable to buy. The TDI wagon is more expensive but if I buy it new I'd probably have it for ten years at a minimum. THe Focus gets 40 mpg on regular gas so it's tough to ignore that but it doesn't drive too nicely. The Passat would be more affordable to buy and would hopefully go for a while before needing any major work although I do most all of my own wrenching. THis is the one I'm looking at

Used 2007 Volkswagen Passat For Sale Milford | Wallingford, Norwalk, CT | P5451

I may go take a look at it but it's three hours away from where I live.

Bart
 
#21 ·
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.
 
#23 ·
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.
 
#25 ·
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
 
#26 ·
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.
 
#27 ·
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.
 
#30 ·
"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...