Hypothetical for petrol 5 owners....road trip with no premium gas
09-30-2015, 01:39 PM
#1
AudiWorld Member
Thread Starter
Hypothetical for petrol 5 owners....road trip with no premium gas
Not to start a gas grade or ethanol vs nonethanol argument, please, but what would happen if you were on a road trip and had to run 87 or 88 octane in the Q5 or SQ5? I'm talking a full tank or more.
Have any of you done this?
What performance changes did you notice driving leisurely or aggressively?
Any documented combined gas mileage decrease?
Presuming most of us don't dyno the car when running 88 octane, and seat of the pants dyno is rarely accurate for obvious reasons, but have any of you realized "whoa, this thing is a pig" when not running 91 for example (we rarely have 93 in our region) or were you like "hey, everything is the same and now I can use gas which is 30 cents cheaper per gallon, yea!"
Have any of you done this?
What performance changes did you notice driving leisurely or aggressively?
Any documented combined gas mileage decrease?
Presuming most of us don't dyno the car when running 88 octane, and seat of the pants dyno is rarely accurate for obvious reasons, but have any of you realized "whoa, this thing is a pig" when not running 91 for example (we rarely have 93 in our region) or were you like "hey, everything is the same and now I can use gas which is 30 cents cheaper per gallon, yea!"
09-30-2015, 02:17 PM
#2
AudiWorld Member
Not to start a gas grade or ethanol vs nonethanol argument, please, but what would happen if you were on a road trip and had to run 87 or 88 octane in the Q5 or SQ5? I'm talking a full tank or more.
Have any of you done this?
What performance changes did you notice driving leisurely or aggressively?
Any documented combined gas mileage decrease?
Presuming most of us don't dyno the car when running 88 octane, and seat of the pants dyno is rarely accurate for obvious reasons, but have any of you realized "whoa, this thing is a pig" when not running 91 for example (we rarely have 93 in our region) or were you like "hey, everything is the same and now I can use gas which is 30 cents cheaper per gallon, yea!"
Have any of you done this?
What performance changes did you notice driving leisurely or aggressively?
Any documented combined gas mileage decrease?
Presuming most of us don't dyno the car when running 88 octane, and seat of the pants dyno is rarely accurate for obvious reasons, but have any of you realized "whoa, this thing is a pig" when not running 91 for example (we rarely have 93 in our region) or were you like "hey, everything is the same and now I can use gas which is 30 cents cheaper per gallon, yea!"
09-30-2015, 05:29 PM
#3
AudiWorld Senior Member
The Q would be fine and you'd have $6.00 more to spend when you got to...
09-30-2015, 06:18 PM
#4
AudiWorld Super User
Had to run regular 87 during Sandy in my S4. No problems. I avoided getting on it since I knew I was running 87.
10-01-2015, 01:48 AM
#5
No harm to the engine, although I'd personally only purchase a top tier fuel
10-01-2015, 04:34 AM
#6
AudiWorld Senior Member
If you're just cruising at a steady speed on the highway, you aren't putting much load on the engine so it doesn't need the knock resistance of 91+, and should run on 89 or even 87 just fine.
I've actually run a couple of tanks of 89 under light conditions like that in my A6 2.0T and the mileage I got was:
562.5 mi / 17.623 gal = 31.9 mpg
521.6 mi / 16.511 gal = 31.6 mpg
And my overall average over 35k mi under all driving conditions using 93 octane 95% of the time is 31.7 mpg. So there really was no difference within normal variability.
However, if you drive aggressively, such as in town with lots of acceleration and the super/turbocharger is providing lots of boost, then the engine will probably start knocking. I believe the ECU is so aggressive with boost and ignition timing that I've even heard it knock on 93 octane with a hot engine when accelerating moderately fast from a traffic light. After the knock the ECU will dial back the boost and timing, but you won't be getting as much power.
Edmunds dynoed a 2010 VW GTI with the 2.0L 4 cyl turbo on 87 octane and it lost about 5% of hp and torque, which is of course at full throttle.
The Effect Of Octane On Its Power - 2010 Volkswagen GTI Long-Term Road Test
I've actually run a couple of tanks of 89 under light conditions like that in my A6 2.0T and the mileage I got was:
562.5 mi / 17.623 gal = 31.9 mpg
521.6 mi / 16.511 gal = 31.6 mpg
And my overall average over 35k mi under all driving conditions using 93 octane 95% of the time is 31.7 mpg. So there really was no difference within normal variability.
However, if you drive aggressively, such as in town with lots of acceleration and the super/turbocharger is providing lots of boost, then the engine will probably start knocking. I believe the ECU is so aggressive with boost and ignition timing that I've even heard it knock on 93 octane with a hot engine when accelerating moderately fast from a traffic light. After the knock the ECU will dial back the boost and timing, but you won't be getting as much power.
Edmunds dynoed a 2010 VW GTI with the 2.0L 4 cyl turbo on 87 octane and it lost about 5% of hp and torque, which is of course at full throttle.
The Effect Of Octane On Its Power - 2010 Volkswagen GTI Long-Term Road Test
10-01-2015, 02:41 PM
#7
If you're just cruising at a steady speed on the highway, you aren't putting much load on the engine so it doesn't need the knock resistance of 91+, and should run on 89 or even 87 just fine.
I've actually run a couple of tanks of 89 under light conditions like that in my A6 2.0T and the mileage I got was:
562.5 mi / 17.623 gal = 31.9 mpg
521.6 mi / 16.511 gal = 31.6 mpg
And my overall average over 35k mi under all driving conditions using 93 octane 95% of the time is 31.7 mpg. So there really was no difference within normal variability.
However, if you drive aggressively, such as in town with lots of acceleration and the super/turbocharger is providing lots of boost, then the engine will probably start knocking. I believe the ECU is so aggressive with boost and ignition timing that I've even heard it knock on 93 octane with a hot engine when accelerating moderately fast from a traffic light. After the knock the ECU will dial back the boost and timing, but you won't be getting as much power.
Edmunds dynoed a 2010 VW GTI with the 2.0L 4 cyl turbo on 87 octane and it lost about 5% of hp and torque, which is of course at full throttle.
The Effect Of Octane On Its Power - 2010 Volkswagen GTI Long-Term Road Test
I've actually run a couple of tanks of 89 under light conditions like that in my A6 2.0T and the mileage I got was:
562.5 mi / 17.623 gal = 31.9 mpg
521.6 mi / 16.511 gal = 31.6 mpg
And my overall average over 35k mi under all driving conditions using 93 octane 95% of the time is 31.7 mpg. So there really was no difference within normal variability.
However, if you drive aggressively, such as in town with lots of acceleration and the super/turbocharger is providing lots of boost, then the engine will probably start knocking. I believe the ECU is so aggressive with boost and ignition timing that I've even heard it knock on 93 octane with a hot engine when accelerating moderately fast from a traffic light. After the knock the ECU will dial back the boost and timing, but you won't be getting as much power.
Edmunds dynoed a 2010 VW GTI with the 2.0L 4 cyl turbo on 87 octane and it lost about 5% of hp and torque, which is of course at full throttle.
The Effect Of Octane On Its Power - 2010 Volkswagen GTI Long-Term Road Test
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07-17-2016, 08:26 PM
#8
Although I don't object to say...89 octane in a pinch, most "super" vehicles are calibrated for 91, but on the highway, you can load the engine pretty heavily.
My informed opinion is that octane needs depend on driving style. Take a monster ride like a old stock Passat 1.8t, my mom could drive around on it fine with mid grade gas, if I were driving it, super would be a necessary evil.
A open throttle plate (if you have one), means more charge which means when it gets compressed, there is more total pressure, thus the need for octane, which is simply a measurement of *resistance to detonation* (from compression).
There is no difference in "quality" between grades, despite the moniker "premium" or whatever. Higher octane mixes have more cleaners because they NEED them, it burns more slowly and leaves more deposits!
Also, most ALL gas comes from a pipeline, the same feedstock. Petrol companies simply keep track of who puts how much into the pipeline, then they pull the same amount out the other end, raw gas....is raw gas.
The final product is blended or "treated" at the distribution terminal, right in the trucks. The driver has a key which corresponds to each brand's additive and octane pack. He or she simply inserts the key and the additive is dispensed right into the rig.
Different brands may have a proprietary additive package or just the generic "EPA" minimum additives. Of course it's extra complicated in the 21st century by local and state regs, requiring localized blends and raising the cost for the consumer. Keep in mind the "Top Tier" fuel that's recommended by most mfgs. TT isn't necessarily the best gas available. Some excellent formulations come from Shell and BP (Amoco chemists). TT has been flopping around like a fish out of water, different brands come and go. Ideally, it's an economical way for a few local brands to share a add pack that is better than EPA min.
What else is out there? Well, a very simple and cheap fuel additive is 2-Cycle oil w/TCW-3 spec. Use it like any "top oil" in the gas at 500:1 (double the first time to coat the fuel system) that's 3oz/10G. TCW-3 spec is "ashless", which is awesome, and it has more and better of the same additives in gasoline, inc stabilizers and surfactants that improve burn. Protects against corrosion from alcohol by physical barrier and....anti-corrosives. It's a big deal if you're using corn gas. If you want to go mental, get the PZ Marine grade of 2C with organic biolube base oil and no organo-metallic additives.
I buy mine cheap at W*M by the gallon, oh $12...it comes out to $.25c to treat 10G or +$02.5c a gallon of gas. If you burn oil, I highly recommend it at whatever treat rate is needed. I use it and burn zero oil in any of my cars.
My informed opinion is that octane needs depend on driving style. Take a monster ride like a old stock Passat 1.8t, my mom could drive around on it fine with mid grade gas, if I were driving it, super would be a necessary evil.
A open throttle plate (if you have one), means more charge which means when it gets compressed, there is more total pressure, thus the need for octane, which is simply a measurement of *resistance to detonation* (from compression).
There is no difference in "quality" between grades, despite the moniker "premium" or whatever. Higher octane mixes have more cleaners because they NEED them, it burns more slowly and leaves more deposits!
Also, most ALL gas comes from a pipeline, the same feedstock. Petrol companies simply keep track of who puts how much into the pipeline, then they pull the same amount out the other end, raw gas....is raw gas.
The final product is blended or "treated" at the distribution terminal, right in the trucks. The driver has a key which corresponds to each brand's additive and octane pack. He or she simply inserts the key and the additive is dispensed right into the rig.
Different brands may have a proprietary additive package or just the generic "EPA" minimum additives. Of course it's extra complicated in the 21st century by local and state regs, requiring localized blends and raising the cost for the consumer. Keep in mind the "Top Tier" fuel that's recommended by most mfgs. TT isn't necessarily the best gas available. Some excellent formulations come from Shell and BP (Amoco chemists). TT has been flopping around like a fish out of water, different brands come and go. Ideally, it's an economical way for a few local brands to share a add pack that is better than EPA min.
What else is out there? Well, a very simple and cheap fuel additive is 2-Cycle oil w/TCW-3 spec. Use it like any "top oil" in the gas at 500:1 (double the first time to coat the fuel system) that's 3oz/10G. TCW-3 spec is "ashless", which is awesome, and it has more and better of the same additives in gasoline, inc stabilizers and surfactants that improve burn. Protects against corrosion from alcohol by physical barrier and....anti-corrosives. It's a big deal if you're using corn gas. If you want to go mental, get the PZ Marine grade of 2C with organic biolube base oil and no organo-metallic additives.
I buy mine cheap at W*M by the gallon, oh $12...it comes out to $.25c to treat 10G or +$02.5c a gallon of gas. If you burn oil, I highly recommend it at whatever treat rate is needed. I use it and burn zero oil in any of my cars.
Last edited by Audi Junkie; 07-17-2016 at 08:32 PM.
07-18-2016, 04:24 AM
#10
AudiWorld Senior Member
Also I have been in the synthetic oil business and outboard racing for many years and can tell you that the Pennzoil marine synthetic is the dirtiest oil you can buy judging from what engines look like when torn down. I wouldn't put that crap in a any outboard and certainly not in my nice Audi.
