Best Grade of Gasoline

[FlyingVolvo]

Some have reported that mid-grade (89,90) works well in their vehicle and probably so, but the ethanol loves our rubber hoses and seals.

Most high-grade fuel in the US is not exempt from the ethanol blend. Almost every Shell 91/93 I've seen has it, except in Canada.

[matthew1]

Filled up yesterday, Shell (like always), 91 grade (max)... with 10% ethanol. Thanks Congress.

[Rattnalle]

I drove my 95 854 for two years and something like 30000 km on pure E85. Used the larger turbo injectors and the ecu compensated for the rest. No other mods. No issues apart from a bit harder to start when it was cold out. Went back to petrol when it became cheaper again and drove another two years with no ill effects that I could find.

[abscate]

I can get Sunoco 93 no ethanol 1/8 mile from my house

[WhatAmIDoing]

Some have reported that mid-grade (89,90) works well in their vehicle and probably so, but the ethanol loves our rubber hoses and seals.

Unfortunately by new government mandate, in the USA all gas will be 10% ethanol minimum, some stations I've seen are even going to 15%. Some stations and boat marinas sell 90 octane ethanol free, but it's expensive compared to 93 octane. You can buy additives that counter-act the effects of ethanol. I think Top Tier fuels have these additives. I wish the US would stop putting ethanol in gas, it significantly kills fuel economy.

I frequently buy 91 octane from Marathon and Sunoco if there's a big enough price difference from 93 (usually it's only a few pennies, so why not 93). Both are considered Top Tier now, so I don't feel as bad, and they are always much cheaper than Shell/BP. Unfortunately, I buy a lot of 89 when I can't justify the >$0.50+ markup for 93 compared to 89, or if I'll be doing all city driving at low revs. The thought of getting 16mpg on a full tank of 93 makes me and my wallet cringe.

[MrAl]

Hello,

Are you guys saying that ethanol hurts gaskets and hoses or helps gaskets and hoses?
If it is good, no problem, but if it is bad, how bad is it?

Also, apparently we loose gas mileage? How much do we loose?

[abscate]

You can calculate this by looking up the fuel value of ethanol, comparing it to the fuel value of gasoline, then weighting the loss by 10%.

Then compare it to the gains claimed by people using " pure gas" and you will find that everything on the internet isn't true.

I believe Volvo says up to 10% ethanol is ok.

[nickelghandi]

Some have reported that mid-grade (89,90) works well in their vehicle and probably so, but the ethanol loves our rubber hoses and seals.

Let me amend my comment a bit. The statement regarding the ethanol should have been below the statement about mid-grade fuel and not separated but the ", but" conjunction. Bad grammar on my part. Yes, 10% up to 15% ethanol is in most fuels now whether it is low or high grade. The point I was trying to make is that the additives in the higher grade fuels do prevent some of the ill effects of ethanol. I was reiterating that from a previous post, but did not allude to it enough.

I am going to try to answer this weighing in on the political aspect as little as possible. Congress is congress and will continue to make good and bad decisions.

Ethanol does harm rubber and lowers efficiency. It does burn "cleaner" by releasing fewer noxious and fewer post combustion chemicals. But the chemicals released are still greenhouse gases. Gasoline will burn just as cleanly if burned in pure oxygen.

Octane (gasoline) burns as follows:

C8H18 + 12.5 O2 --> 8 CO2 + 9H20 Yielding about 45 megajoules of energy per kilogram of gasoline (equation written using stoichiometric amounts)

The only emissions are Carbon Dioxide and Water. Pretty clean, right? Until you take into account the fact that octane isn't burning in pure oxygen in our engines. Our atmosphere is only composed of about 21% Oxygen and most of the rest is Nitrogen. Nitrogen is what causes those noxious emissions (see what I did there? ) The NOx (Nitrogen + undetermined amount of Oxygen) emissions are what the US Government is trying to reduce while simultaneously padding the pockets of corn producers. Ethanol is also a fantastic alternative to lead as an additive in fuel to increase combustion resistance.

Ethanol production also yields food so maybe padding the pockets of corn producers isn't so bad? Not 100% sure on that one. More research needed.

Now, Ethanol which is highly miscible in petroleum and other organic compounds (including: gasoline, oil, RUBBER, etc.) burns very cleanly at STP (standard temperature and pressure). Ethanol burns as follows:

CH3CH2OH + 3O2 --> 2CO2 + 3H2O yielding about 23 megajoules of energy per kilogram of ethanol (equation written using stoichiometric amounts)

From looking at the information above, we can see that ethanol produces roughly half the energy of gasoline when burned, however also notice how little oxygen is required to burn ethanol. This is what results in fewer NOx emissions. Ethanol is able to take advantage of the oxygen available rather than reacting with the Nitrogen that is also present in the engine.

Gasoline containing ethanol WILL burn cleaner. It WILL be less efficient on most engines. It WILL eat at rubber seals and hoses over time without additives.

I pulled the equations from my 5+ year neglected chemistry knowledge, but some quick googling found a really good paper from Princeton regarding octane. You can look at that right here: https://www.princeton.edu/ssp/64-tiger- ... pdated.pdf

All of this information can be found on the web and you should do your own research and draw your own conclusions, but this lengthy post is my opinion on it being as objective and factual as I can be.

My personal and nonscientific opinion is that ethanol does in fact help my Volvo and make it significantly more efficient, considering how much of it I consume while working on my S70.

[Rattnalle]

Agree with the last point there

We've had ethanol in the petrol over here for a long time now and I haven't really heard any reports of actual issues related to it yet. But old cars break eventually either way and telling exactly what does it is a very inexact science.

[WhatAmIDoing]

Ethanol production also yields food so maybe padding the pockets of corn producers isn't so bad? Not 100% sure on that one. More research needed.

Gasoline containing ethanol WILL burn cleaner. It WILL be less efficient on most engines. It WILL eat at rubber seals and hoses over time without additives.

Corn produced for ethanol cannot be used for human food. Some of what's left can be used as cattle feed, but it's minuscule compared to forage corn grown for feed. There is a big argument as to whether corn should be grown for ethanol or used as food. 8 bushels of corn = 21.6 gallons of ethanol or (not and) enough food to feed 1 person for a year.

Ethanol decreases energy efficiency of pure gas by principle of dilution, so you will get less mpg on 15% ethanol than 10%, than 5%. I'm okay with 5%. Most modern cars are tuned for high ethanol gas, older cars, however, were not designed with the thought of 10%+ ethanol.

I believe Volvo says up to 10% ethanol is ok.

My manual with a 1997 print date sates 5% ethanol maximum. I do not know if Volvo later released a rectification of maximum ethanol content for 1998 and prior models.