Which is better - 90 octane no ethanol or 93 octane 10% ethanol

-

66fyssh

Don't Stop Believin'
FABO Gold Member
Joined
Jun 22, 2013
Messages
8,338
Reaction score
9,813
Location
Fort Walton Beach, Florida
I just moved from Virginia to Georgia and there is a Valero gas station near my house that sells ethanol free gas, but only up to 90 octane.

I was running 93 octane, 10% ethanol in my 273 Commando in Virginia. Seemed to run great, just a little hard hot starting.

I wanted to get your thoughts before my first fill up in Georgia!
 
You asked the same question on a subject I was curious about. There is a station just opened close to my house that sells 90 octane non ethanol gas.
 
Cool. I was excited at first, then bummed when it was only 90.

I wanted to hear from some folks with experience before I fill up.
 
I quit running 93 with ethanol
Switched to 90 no ethanol. Def way to go. Ethanol is hard on fuel system if they sit.
Especially small engine like mowers. Chain saws. Etc.
I say 90 no ethanol is my choice. I run it in my 75 408 duster driver and it ran 11.0's at drag strip on it.
 
The alcohol increases the octane rating. Try 5 gallons of each but I'll bet you will like the non ethanol in the old cars we drive. I use premium non alcohol and still have fuel evaporation issues after setting a few days.
 
Thanks guys! If it works in a 408 it should work in a little 273!

I'll try a half tank of the non ethanol and let you know what I find.
 
Does the engine need the higher octane? If not, run the 90 w/o ethanol. You'll get better mileage from the lower octane and the higher btu content of the fuel from not having etoh.
 
Yeah ^^^, I'm gonna look for some around here. I can't stand the gas-a-hol. It eats everything rubber in sight.

I have had frightful times with my trimmers, blowers, chain saws etc. My mower is new enough and I believe designed to run on it.

I took some of the crap from a local store here and put about an inch or so of it in a paint can cap on a hot and humid afternoon. I let it sit overnight on my workbench, and when I went to the garage the next day that cap was bone friggin dry, it had evaporated overnight.
 
The non-eth near me is only 89.

I've run both in my 69 440.

No big difference in performance and cost difference used to be big, but not as much now, so I've been mixing them about 50/50.

Should be 91 oct and 5% eth.
 
The non-eth near me is only 89.

I've run both in my 69 440.

No big difference in performance and cost difference used to be big, but not as much now, so I've been mixing them about 50/50.

Should be 91 oct and 5% eth.

If I may ask, what are you paying for the 90 octane non-ethanol ?
 
Non ethanol is refered to in the industry as "recreational" gas. Started out to be used at marinas, and was very costly. I was told by the Marathon rep that it cost more to add the ethanol, then he told me it cost more to leave it out for the rec fuel. Go figure huh. Any hoo, it is a good product and if it can be had near you, I would run it....
 
OP: really depends on what your car is tuned to run. If it runs satisfactorily on E10, either keep running it that way, or try adding 4-5 gals to 1/4 tank when you get down that far. The example I'm about to use is like apples to oranges, but at least they're both still fruit...after driving my pickup for several months using midgrade 89 E10 fuel, I fueled up at a station out of town with a non-alcohol blend. Overall, the truck ran fine, but it started pinging little...never did that on the E10 fuels. Now, that being said, we're talking a modern engine with EFI and knock sensors and programmed to adapt for ethanol blended fuels, so it was able to compensate but with slighted performance since timing was readjusted to reduce the spark knock. Long story short, I ran the tank down as far as I could with that fuel and then filled back up with my regular stop.

BLUF: If you're setup to run real gas, you'll be fine, if it's been running good with E10, I'd be measured about how much I put in there and pay close attention to the way it responds, otherwise--go for it
 
Ethanol draws water, has a higher octane, has a lower stoichiometry (that is why E85 users need to run what would be richer compared to gasoline) and does not lubricate as well as gasoline. Here in Oregon, we have up "to 10%", so you may never get a true E10. I have never had one issue with any of my older cars or power equipment, even when sitting for long periods with 87, 90, or 92 octane.

Regardless of composition, gasoline will degrade while sitting open to atmosphere. Its octane actually lowers during evaporation.
 
I have found with ethanol based fuels to use fuel stable with every tank.
It goes along way to prevent problems, use it in every can for the lawnmower, weed-eater and antique cars.
 
Up here in the great white north our 87 and 89 octane has "up to 10%" ethanol, but the high test (91 and above) has no ethanol.

For me, if I'm going to use the gas relatively soon I'll just buy the cheap stuff. I run the 87 octane at normal fill-ups, but when I'm putting the car away for the winter I always use the non-ethanol gas plus a bottle of stabilizer.

Whenever I fill a gas can (for the snow blower, lawn mower, weed whacker, generator) I always use the high test plus stabilizer.

So if I had your options I would go with the 90 octane, no ethanol. Unless you NEED the extra octane to prevent detonation.
 
I've been running 87E10 since 2000, No problem-o. It has not harmed any part of the fuel system. I put stabilizer in the last tankful of the year. Car starts right up in spring.Without stabilizer this fuel has a short shelf life, unless it is in a sealed container.
 
i solved the methanol trouble by useing Marvel Mystery Oil. 4 oz in 10 gal of gas. and an other way to get the MMO in is to check this product out. WWW.ampcolubes.com its is like the old organal Marvel Mystery oil top oiler. with the MMO my engine seams to start very fast.
 
Great info!

I made it out today to get some 90 octane, non ethanol. I had the car near empty for towing it to Georgia. I pumped in 6.5 gallons since it was such a PITA. The pumps are new and pump much too fast for the a-body!

Price was $3.05/gal using my debit card. Some stations still have a cash price and charge price here, and Valero is one of them...go figure! I'll check the cash price next time I'm there.

93 Octane with up to 10% ethanol is running $2.57/gal at the stations with the same price, cash or card.

I wasn't getting detonation using 93 with ethanol. I'm at about 14* initial and 36* mechanical timing with a 273 Commando.

I'll run this for awhile and see how it runs. Thanks for the input!

Toad
 
It depends on if you need the octane and alcohol or not. I like the the 93 ethanol fuel. My 500ci motor diesels horribly when shutting it off hot with 91 non eth fuel but does not with 93 eth. I agree that the ethanol fuels do go bad faster and clog up and fuel system but that is preventable with additves in the off season.
 
It depends on if you need the octane and alcohol or not. I like the the 93 ethanol fuel. My 500ci motor diesels horribly when shutting it off hot with 91 non eth fuel but does not with 93 eth. I agree that the ethanol fuels do go bad faster and clog up and fuel system but that is preventable with additves in the off season.


Thanks! I like to drive it as much as possible as long as it's dry out. I should know soon if it's going to ping or diesel with the 90.
 
OK, after 150 miles using non-ethanol gas, I've determined my car likes non-ethanol much better! I'm glad its available here, didn't see any in Virginia.

The biggest change is on starting. The motor now fires almost immediately!! It's really amazing how much difference there is on initial start up. It costs more but since I don't drive it everyday, I can swing it.

It still take some cranking on hot starts. I just open the throttle as its cranking and it starts. Need to try a spacer on the carb, I guess.
 
In tests around my parts the actual alki content in fuel is around the 6 to 7% range. I've read that it's rarely right at 10%.
 
I've seen the signs that usually read "up to 10%".

It does fire much quicker now that I changed over. I moved from sea level to about 1200 ft so I adjusted the A/F level. That could have helped some also.
 
-
Back
Top