Fuel - Premium or Regular?

[CA Touareg]

Thanks for the comments. I personally feel I get better MPG's when I use Premium. I notice a big difference in power also. When I used regular fuel I really had to put my foot in it to get it moving therefore canceling any financial gain in using regular.

I agree that using Premium is best for the engine also. I talked with a VW Tech and he said regular will not hurt the engine but I would rather play it safe.

[imorgan]

Nothing but Preium here !!

[CA Touareg]

I just found this information on Carbibles.com. Just thought it could help with this discussion.

Octane and gas mileage
Here's a good question : can octane affect gas mileage. The short answer is absolutely, yes it can, but not for the reasons you might think. The octane value of a fuel itself has nothing to do with how much potential energy the fuel has, or how cleanly or efficiently it burns. All it does is control the burn. However, if you're running with a petrol that isn't the octane rating recommended for your car, you could lose gas mileage. Why? Lets say your manufacturers handbook recommends that you run 87 octane fuel in your car but you fill it with 85 instead, trying to save some money on filling up. Your car will still work just fine because the engine management system will be detecting knock and retarding the ignition timing to compensate. And that's the key. By changing the ignition timing, you could be losing efficiency in the engine, which could translate into worse gas mileage. Again as a practical example, my little tale above about our trip to Vegas on low octane gas. (Whether you want to believe some bloke on the internet or not is up to you). On the low octane gas on the trip down, we could barely get 23.5mpg out of the Subaru. Once I was able to fill it up again with premium at the recommended octane rating, we got 27.9mpg on the way back. A difference of 4.4mpg over 450 miles of driving.
Doing the maths, you can figure out that by skimping on the price during fill-up, you may save a little money right there and then, but it costs in the long term because you're going to be filling up more often to do the same mileage. My advice? Do what the handbook tells you. After all it's in the manufacturers better interests that you get the most performance out of your car as you can - they don't want you badmouthing them, and in this day and age of instant internet gratification, you can bad-mouth a large company very quickly and get a lot of publicity.

[CA Touareg]

Just a little more proof we need to keep using Premium:

Octane and power
It's a common misconception amongst car enthusiasts that higher octane = more power. This is simply not true. The myth arose because of sportier vehicles requiring higher octane fuels. Without understanding why, a certain section of the car subculture decided that this was because higher octane petrol meant higher power.
The reality of the situation is a little different. Power is limited by the maximum amount of fuel-air mixture that can be jammed into the combustion chamber. Because high performance engines operate with high compression ratios they are more likely to suffer from detonation and so to compensate, they need a higher octane fuel to control the burn. So yes, sports cars do need high octane fuel, but it's not because the octane rating is somehow giving more power. It's because it's required because the engine develops more power because of its design.
There is a direct correlation between the compression ratio of an engine and its fuel octane requirements. The following table is a rough guide to octane values per engine compression ratio for a carburettor engine without engine management. For modern fuel-injected cars with advanced engine management systems, these values are lowered by about 5 to 7 points.

Compression ratio Octane
5:1 72
6:1 81
7:1 87
8:1 92
9:1 96
10:1 100
11:1 104
12:1 108

I think the V6 has a compression ratio of 12:1. Does that mean we should be using 101 octane?

[Godwine]

12:1 is really high. But yes, its best to be using 100+ octane for this car. I think we get better mileage from it. But it is a pain in the butt to order these type of fuel in canada. Anything beyond 96 is considered racing fuel, you cannot get it from the pump, you can order it, but you need either a shop or have a valid race car license

[CA Touareg]

Thanks Godwine

[Vegas Matt]

We used to have 100-octane (104 RON) at the pumps here in Vegas. When premium (91 octane (R+M)/2 (95 RON)) was at $2.40 a gallon, it was $4.25 a gallon! I'd hate to fill up a Touareg with that stuff! It did do well in my 2-stroke pre-mix for my old dirtbike, it seemed to burn cleaner and the engine ran more smoothly on the 100-octane gas.

Overall, though, I'd run what's recommended. 91 to 94 would all be good, 100 may be overkill, but it would be interesting to see what the 100-proof would do to fuel economy and performance.

Matt

[CA Touareg]

I would also love to see what the 100 proof would do for performance. The price of it is way too high for my blood though.

[markluke]

Originally Posted by Vegas Matt

We used to have 100-octane (104 RON) at the pumps here in Vegas. When premium (91 octane (R+M)/2 (95 RON)) was at $2.40 a gallon, it was $4.25 a gallon! I'd hate to fill up a Touareg with that stuff! It did do well in my 2-stroke pre-mix for my old dirtbike, it seemed to burn cleaner and the engine ran more smoothly on the 100-octane gas.

Overall, though, I'd run what's recommended. 91 to 94 would all be good, 100 may be overkill, but it would be interesting to see what the 100-proof would do to fuel economy and performance.

Matt

At the Deltasonic car wash I used a few weeks ago in Niagara Falls, NY they sell 100 octane for over $5 a gallon. I stuck with 93 for $2.83

[bibliothyle]

I've typically run premium fuel cars on regular gas with no problem. No so with the Touareg. After 5000 miles the engine ran very rough and almost quit while driving at about 3000 ft. altitude. Putting premium in solved the problem and hurt my pocket book.