I did this for 3 months. Found no noticeable decrease in performance but mileage dropped by 3mpg. My car has 115k and is a 99 V6 MT.

 

i haven't used premium regularly for almost a year and a half.. haven't had any issues.. i'm not chipped and dont have any kinda of performance intake or exhaust... I run on the 89 with ethanol, and for the extra .30 cents i don't notice enough of a difference in performance or gas mileage to justify it.

 

What really hurts is that gas is at or over $4/gal...

1999 Passat Sedan - V6
To start this off, I have started "trying" regular gas lately, and plan to see if I can get some sense of its impact after a few months, and then go back to the correct grade. My findings so far are:

- Been doing this for about 1 - 2 months and ~2k miles
- Have used any brand of gas, but stay away from no-name stations
- Found no noticeable performance difference, but I am not an aggressive driver
- Found my mileage on distance traveling (4-6 hour trip) is the same as before - 27 - 28 mpg
- Found a drop off on in town (1 - 3 miles one way) from 21 or so (mid-winter) to just below 18 - 19 mpg. But I am not sure if this is because the car is due for my 150k maintenance, or just the real short trips which is about all the driving my wife does lately (its her car), or?

Feedback from others on your experience?

Does $2.50 per tank really make a difference in your budget? Think about this, you can only put about 12 -13 gallons in the tank, even after the low fuel warning light comes on. At $.20/gal, the cost savings per tank is $2.40 - $2.60. You could say that overtime it adds up, but only if it does no harm to your engine. Preignition is harmful to your valvetrain.

Are you sensing any preignition (knocking) when the engine is under a load, like hard acceleration? Filling your car and saving $2.50 per tank is purely a psychological advantage that you are doing something to save money.

I don't hear anyone complain that milk is $3.79 - $4.00 per gallon. Increased speculation in the oil market has created this inflation bubble. It bugs everyone. My wife has an '04 Z71 Tahoe. Last year we could fill the tank for a less than $60. Now it costs $83. That hurts more than an extra $.2 per gallon.

I believe we should do what is in the best interest of protecting these depreciating assets we abuse on a daily basis, just by the mere act of driving.

 

03 V6, Tip, 91K, have been running 87 grade for about 7 months (10K). No noticeable difference in performance or MPG.

 

I just switched from 93 (non-ethanol) to 87 (with ethanol), and so far my mpg have been consistently 5-10% lower. However, I need to run a couple tanks of 93 (with ethanol) as a control--I don't know whether the decrease in mpg is due to the sudden appearance of E10 everywhere, or due to the reduction in octane.

Frankly, I suspect it's because of the ethanol. My daily commute is VERY consistent at my new job, so it's easier to run regular tests over time.

 

It has been well documented that E85 is less efficient than regular formula gasoline. I would expect that any addition of ethanol would dilute the efficiency of gasoline.

I will not put that crap in my gas tank when it is no cheaper than gasoline. What is the advantage of using ethanol? Ethanol is a boondoggle and only has driven up the prices of corn foodstuffs.

 

I will not put that crap in my gas tank when it is no cheaper than gasoline. What is the advantage of using ethanol? Ethanol is a boondoggle and only has driven up the prices of corn foodstuffs.

Most of the people around here are anti-ethanol...here I'm talking about the mandatory blend of ethanol (up to E10) that has been replacing MTBE as the preferred additive all over the country over the past couple years. Sure, it makes a marginal difference in emissions, but it causes people to burn more fuel (and spend more money).

 

E10-20 is all but mandatory nowadays, due to oxygenation concerns, and the fact that MBTE is horrendously toxic.

Since the mandating of E10, I rarely get the EPA highway numbers on my mileage unless I start playing around with hypermiling strategies (which will make everyone HATE you).

Yesterday I knew I had roughly 2 gallons of fuel left and a 35 mile drive home. Managed to get 28MPG driving home, and 3/4 of a gallon left in my tank. To do this I never exceeded 65 and kept my accelerations slow and gradual. I'm also running 35psi in the front, and 38 in the rear, so far with no negative effects on traction that I can see.

 

...and the fact that MBTE is horrendously toxic.

As a chemist, I can tell you in the grand scheme of things MTBE isn't all that toxic. We allow other much more toxic chemicals into our water supply as long as their concentrations are low enough. The main issues are MBTE can be detected by humans at very low levels and when MTBE leaks from a storage tank it can end up in the water supply quickly and be detected by the end consumer of water.

 

I didn't know that ethanol was now a requirement in all gasoline, as a replacement for MTBE (Al Gore supported the addition of the environmental scourge MTBE).

Last year several automags did features comparing the fuel efficiency (by MPG) of E85 and gasoline. Fuel efficiency fell appreciably with the use of E85.

The most efficient oil derived fuel is diesel, but at $4.79 a gallon it now has about a $.01 cost per mile advantage over gasoline; according to a recent feature on SUVs in Autoweek.

This discussion is not a hijack of the thread, as it is very important to completely understand all of the implications in fuel choices.

No one has commented whether or not they have had preignition under load running 87 or 89 octane. Preignition would be very noticeable in hot weather, which has been my experience when running the 87 called for in my Tahoe.

 

According to Wikipedia: Gasoline is a mixture of hydrocarbons, although some may contain significant quantities of ethanol and some may contain small quantities of additives such as methyl tert-butyl ether as anti-knock agents to increase the octane rating.

So if MTBE is out, then ethanol is in as a way to raise octane. As Traubenberg stated about ethanol: "It is, however, less engery dense than gasoline.", which is why E85 fuel provides lower mileage.

I have not noticed my mileage change appreciably with the change in the formula of 91-93 octane gasoline. I average about 22 mpg on a tank, and 24-27 mpg at 80 mph on the highway.

 

Ran regular for a year, switched to premium for 8000 miles and noticed no difference in mileage. Been back on regular for 18 months and still no difference.

There was a minor improvement in throttle response with the premium. Not enough to pay for.

 

I still buy the highest octane gas I can find. My V6 feels crippled when I put regular fuel in. It's like when I have to feed my dog some food he's not used to. He's just not right.


There are times when I need maximum performance and response from the engine. In my short experiment with 87 RON fuel I found that the $2.00 saved per tank was not worth the decreased performance.

 

I see the effects of regular vs premium weekly. Carbon deposits, complaints about drops in mileage. The $2-$4 per tank you think you're saving, you're spending in loss of efficiency. You "feel" no appreciable difference in performance because the ecu is adjusting timing,fuel ratio,etc to compensate for the crap you put in your tank. Save $2-$4 per tank, lose 2-3 mpg & performance. Worth it ?

 

Carbon deposits???? So what you are saying is that 87 octane fuel is dirty compared to 91 octane fuel. I'm sorry I just don't buy that one. Octane rating has absolutely nothing to do with how clean or dirty the fuel is.

 

see http://www.passatworld.com/forums/showthread.php?t=244600&highlight=crow+tastes thread.

 

Even though gas is approaching $4.60 in Eugene (raising 2 cents daily) I have never and will never mess with regular in my Passat. I want it to hit 250,000 miles someday and skimping with things like cheap gas and regular oil aren't going to cut it. At the pump, I'm already paying over $50 regardless. Usually I fill up when I hit a quarter-tank and the $2.50 I would save if I filled it with regular is not worth it. I also try not to go to any station except Chevron. 76 once in awhile if I absolutely have to. There might not be a noticeable difference (to us) between regular and premium, I really don't know since I've never used regular, but there's a reason the manual tells us to fill it with 92. It's not because they hate us and want us to throw away money at the gas station, it's because that's what's best for the motor. I don't care if gas gets to $6 or $7 I will always fill it with premium.

 

I used the basic stuff for about a year. I noticed a SIGNIFICANT power and performance decrease. Not to mention had to change my fuel filter out twice in one year. due to the gas prices (going on $4.96 here in the great(hah) LA) I have started to use the middle one, 89 octane I think... Either way, its not 91 octane, but the only noticeable difference is a slow push off the line. Doesn't have that perkiness that it did when I was using the 91.

 

Sorry to tell you but the octane rating had ABSOLUTELY nothing to do with your having to change the fuel filter twice in a year...hmmm maybe that's why you were experiencing a loss of power. When will people understand that 87 octane and 91 octane are the same fuel but that 91 octane just has a higher resistance to preignition(ping) than 87 does. Octane is not some some magical additive that is put in fuel which makes it cleaner and better.

 

one tank of regular after the price topped $4 a gallon here - I have noticed that in stop and go traffic my mileage has dropped from 18 to 15 - but that's just one tank and it's hotter now than it has been so take it for what it's worth...