Shell V-Power 91 0% Ethanol vs Esso Supreme 93 w/ 10% ethanol?

[OppositeLocK]

What is better for preventing carbon build up? I know Shell 91 will give me better mileage because it is pure gas, but will ethanol burn cleaner?

This is for a 2019 WRX with the FA20 engine. Being purely DI I'd like to go with the option that will help slow the onset of carbon build up. I know it's inevitable regardless, just like in Audis, Mercs, BMWs, etc.

I care about performance not MPG. I'd rather go with 93 as I've read this engine on hot days can retard timing even on 91, so would rather have all the headroom I can get. But don't want to if the ethanol will hurt more than help.

 

[JohnnyJohnson]

What is the price, MPG and performance difference? Shell one of the higher price spreads here locally.

 

[OppositeLocK]

Price is negligible between the two. Performance I can't really say, but I assume the 93 octane would get better knock resistance.

 

[ctechbob]

Thought carbon buildup in DI cars was mainly a result of PCV gases baking to the backside of the valves? Hence the rise of the catch-cans.

 

[Gasbuggy]

91 should give you a little more power because of the slightly quicker detonation, factory tune should not induce knock with 91. Better MPG with 91 too no doubt. Is Shell 91 Ethanol Free? I'll start buying it instead if so.

 

[NO2]

Neither gas is going to help with deposits on he intake valves. You'll get a bit more energy from the Vpower.

 

[diyjake]

Originally Posted by Gasbuggy
91 should give you a little more power because of the slightly quicker detonation, factory tune should not induce knock with 91. Better MPG with 91 too no doubt. Is Shell 91 Ethanol Free? I'll start buying it instead if so.


I think that is a Canadian thing only. All shell gas stations i've been to here in PA and the states have ethanol.

 

[Randy_R]

Regarding Shell V-power 91, are all stations 0% ethanol?

 

[Garak]

It depends upon your jurisdiction. If your jurisdiction requires ethanol blending in all gasoline grades, then it will not be 0%. Where it can be 0% and there are no other blending considerations pushing ethanol, it will be 0%.

 

[Snagglefoot]

" Where Available"

 

[Danno]

I'd go with Shell in Ontario.
No ethanol, gives 3% better fuel economy as ethanol has less BTUs than gasoline

 

[mazdamonky]

Originally Posted by Danno
I'd go with Shell in Ontario.
No ethanol, gives 3% better fuel economy as ethanol has less BTUs than gasoline


In theory yes, however it doesn't always seem this way in practice. Both my 2018 Mazda 3 and 1985 mazda RX7 see at least a 10% bump in fuel economy when using Murphy USA non ethanol 91 vs other premium nonethanol gases. My standard gas mileage in my 85 rx7 is around 18-20. The moment I use any grade of nonethanol I am often seeing 22-24 under the same driving conditions. The moment I put an e10 based gas in, it goes back to the lower fuel economy ratings.

I make the same 2.5 hour drive 3 times a week and drive 77 mph. On anything non-ethanol I will see 34.5-35.7 mpg depending on weather or whatever other variables there are. The moment I drop in Walmart/Murphy 91 nonethanol it goes up to 39+ mpg almost every time with repeatable results.

 

[Danno]

Originally Posted by mazdamonky
Originally Posted by Danno
I'd go with Shell in Ontario.
No ethanol, gives 3% better fuel economy as ethanol has less BTUs than gasoline


In theory yes, however it doesn't always seem this way in practice. Both my 2018 Mazda 3 and 1985 mazda RX7 see at least a 10% bump in fuel economy when using Murphy USA non ethanol 91 vs other premium nonethanol gases. My standard gas mileage in my 85 rx7 is around 18-20. The moment I use any grade of nonethanol I am often seeing 22-24 under the same driving conditions. The moment I put an e10 based gas in, it goes back to the lower fuel economy ratings.

I make the same 2.5 hour drive 3 times a week and drive 77 mph. On anything non-ethanol I will see 34.5-35.7 mpg depending on weather or whatever other variables there are. The moment I drop in Walmart/Murphy 91 nonethanol it goes up to 39+ mpg almost every time with repeatable results.


That could also mean the so called 10% ethanol gas has more than 10% ethanol ....

 

[Speak2Mountain]

If I could get Shell V Power in 100% gasoline, I'd buy it in a NY minute. I doubt your car will know the difference between 91 and 93.

 

[Speak2Mountain]

If you want to prevent carbon build up...

1) Run the crap out of your car when its warmed
2) Use a low Noack oil.....use Bitog
3) Run your car long stretches on high speeds
4) Limit stop and go
5) Move to Dixie
6) Install a catch can.

 

[Ded Mazai]

What is the recommended octane number for your car? My car runs better on Petro 94. Esso 93 knocks sometimes and the ignition timing is pulled back. I my opinion any gas which doesn't give knocking is better no matter how they blend it.

 

[OppositeLocK]

That's the thing. So the OM says 91 for performance but that it could run on 87 without affecting the warranty. I think buying a WRX and running 87 is pretty dumb so going to stick with 91 minimum.

But I've heard from reviews and forums that the FA20 engine will pull timing on even 91. So I'd rather run 93 and get slightly worse fuel economy but better performance. But I'd rather not do that if ethanol will speed up carbon build up.

 

[Ded Mazai]

I tried almost all gas types in Toronto and I did not see any advantages in ethanol free gas compared to Esso93 or Petro94 regarding the fuel economy. But I did see much worse fuel economy on 87 gas. My engine is FA20 @ 12.5 compression ratio so my experience may not apply to your case 100%. I suspect that if Esso93 and Petro94 contain some ethanol the amount of it may be well below 10%. I am pretty sure that retarding the ignition will lead to spark plug fouling and carbon build up a lot more than anything else. On the other hand, you may be wasting the money running Esso93 or Petro94 if the ignition gets pulled back very seldom. In my case Petro94 has clear advantage over Esso93 at the same price.

 

[Patman]

Originally Posted by JohnnyJohnson
What is the price, MPG and performance difference? Shell one of the higher price spreads here locally.


In my immediate area I have noticed that Shell is now priced at a 24 cent premium over regular, while the one station near me that carries Esso 93 is priced at only 21 cents above premium (plus that station already has it's regular priced a few cents per liter less than Shells in the area) So for me I've been running Esso 93 in my Corvette lately, although I will switch back to ethanol free 91 (mostly from Costco) in the fall and for the winter storage period.

 

[Surestick]

Originally Posted by Ded Mazai
I tried almost all gas types in Toronto and I did not see any advantages in ethanol free gas compared to Esso93 or Petro94 regarding the fuel economy. But I did see much worse fuel economy on 87 gas. My engine is FA20 @ 12.5 compression ratio so my experience may not apply to your case 100%. I suspect that if Esso93 and Petro94 contain some ethanol the amount of it may be well below 10%. I am pretty sure that retarding the ignition will lead to spark plug fouling and carbon build up a lot more than anything else. On the other hand, you may be wasting the money running Esso93 or Petro94 if the ignition gets pulled back very seldom. In my case Petro94 has clear advantage over Esso93 at the same price.


Running a lower octane fuel (and therefore retarded ignition timing) is more likely to make your exhaust valves run hotter which, in the long run, could lead to issues.
If the engine management is adding more fuel to prevent detonation than it might lead to plug fouling but I doubt they'd do that in a modern car for emissions reasons (increased hydrocarbons and cat damage). They'd be more likely to limit boost and cut timing.