Which Gasoline?

[Baxterdown]

Hi guys, I've been meaning to ask this question. My car's seller strongly recommended I only put 90 octane ethanol-free gas in my car (1972 w108), which I have done diligently since I bought it earlier this year. He said regular gas will destroy our cars.

Is that so? Is it really necessary to only use ethanol-free gas?

Thanks in advance for your thoughts.

Jose

[Tomguy]

Your friend's 3.5 needs 91 minimum, probably 93. Your 4.5 is supposed to be able to run on 87 (I was always told this) but my 4.5 knocked on anything less than 91. It may depend on your engine condition, timing, and other components. It can also be a factor of if you have the 8.8:1 heads or 8.0:1 heads. It's one of those "YMMV" things.

[bsharp8256]

I always run premium in my Benz gassers...in fact I even put it in my '63 Falcon convertible with the 170 I6. It idles a lot smoother and doesn't have that "cough" that plagues the Ford sixes with the stock log intake.

[Baxterdown]

Thanks for your replies guys. I'm happy to use 93. My main concern is the ethanol. The seller said that it would destroy the tank, lines, engine, etc.

Any thoughts on that?


Sent from my iPhone using Tapatalk

[Tomguy]

Honestly? Ethanol does that to all cars. Sure, modern cars also have plastic tanks and plastic fuel lines, but metal components still get eaten up. It isn't the ethanol, it's the hygroscopic properties of it. In other words, ethanol absorbs moisture from the atmosphere, and it's that moisture that will cause the problems.

[bsharp8256]

From what I understand Tomguy is 100% right. Drive it regularly and keep fresh fuel in and it shouldn't be a problem...I've run ethanol gas for 4 years in my Falcon with no issues. If I know it's going to be off the road for a while I'll get a bottle of fuel additive that specifically states that it protects against water buildup in ethanol-blended fuels and make sure it's run throughout the fuel system before parking it.

[aluminum]

Some consideration for thought :
Ethanol in fact can completely ruin a motor in ways . Ethanol is like a Baby , I think of it as a Government baby just like Smog controls , devices a money maker .
Ethanol ( Corn ) well ruin non compliant Fuel Lines , it brakes them down also many plastics. So Best thing is to change out all Hi Pressure Fuel Lines to Ethanol high pressure Lines . Why ? because if they leak and catch fire your Vehicle and self may burn .
Long term Damage to valves , Motors well happen but it takes a long time .
Most Ethanol Damage :
Well Most damage is due to Ethanol that just sits and is not used , just sitting in a Tank a Line a Injector , some Plastic part that sort of thing . When it sits you have the problem that's why they sell Ethanol Stabilizer .
You Don't add Ethanol Stabilizer when your using the car you add it when your going to let it sit and add it a day before when your still using the car to mix it in good .
Better yet just drain the system all together .
whats sitting a long time ? more then 90 days

[Idle]

Back when the switch to unlead came about, in 1975 or 1976 depending where you were, there was a great deal of concern about valve life. It seems one of the things lead was good for was acting as a cushion for the valve edges. Without the lead it was predicted that the valves would 'recede' into the cylinder head.

As far as I know this has not become a big problem. At least it never was for me and I never had to tear an engine down to install hardened valves.

Anyone have any further info on this subject?

[John Galt]

Originally Posted by Baxterdown

Thanks for your replies guys. I'm happy to use 93. My main concern is the ethanol. The seller said that it would destroy the tank, lines, engine, etc.

I avoid ethanol fuel and run premium in all carburated engines. The EFI engines seem more tolerant of alcohol fuel mixes and their components are more ethanol resistant.

[Graham]

Originally Posted by Baxterdown

Hi guys, I've been meaning to ask this question. My car's seller strongly recommended I only put 90 octane ethanol-free gas in my car (1972 w108), which I have done diligently since I bought it earlier this year. He said regular gas will destroy our cars.

Is that so? Is it really necessary to only use ethanol-free gas?

Thanks in advance for your thoughts.

Jose

I have a 72 107. I have run it on regular 87 gas for past 25 years. No affect on fuel systems or engine.

One thing ethanol may affect, is mixture control. Modern cars have feedback from exhaust composition, but our old cars do not. Ethanol reduces stoichiometric ratio for the fuel, so original 1972 %CO figures may not be optimum. I have found that running on slightly rich side at idle and under load gives good performance and helps reduce hot start problems.

Here in Canada, I believe regular has "up to" 10% ethanol.

[Idle]

When the switch to unlead came about the new fuel would sometimes eat up the accelerator pump in some cars. Chrysler products were very prone to this.

By now everything on the road would have had its' carb rebuilt, but if you are bringing an old car out of a long sleep with today's unleaded fuel this can be an issue.

[berfinroy]

Beginning in 1972 and for some years thereafter Mercedes was forced to reduce the compression ration in all its USA bound cars from 9/9.5:1 to 8:1 to meet US emissions requirements. An 8:1 engine that doesn't have excessively advanced ignition timing shouldn't require premium fuel.

[Baxterdown]

Guys, thanks for your replies! I'm confused now... Doesn't premium have ethanol in it too? From what I'm reading you guys are saying that it doesn't. If that's the case I'll just switch to premium for my car.

I had asked the original question because the nearest gas station that sells ethanol-free 90 gas is 7 or 8 miles away. So it's a pain to get gas. If 93 premium doesn't have ethanol, I'm good!?!?

[Marrs]

One addition, I use Sta-bil Ethanol Treatment, NOT to be confused with the fuel stabilizer. The Treatment specifically prevents the phase separation, or the release of water the fuel has absorbed, so it helps protect the exposed tank and other elements by making sure the water is burned as part of the combustion process rather than being left in-tank. My car starts and runs so much better now that I use this in every single tank, one $6 bottle lasts me about 4-5 tanks I believe based on the recommended concentrations/dilution.

[John Galt]

Originally Posted by Baxterdown

Guys, thanks for your replies! I'm confused now... Doesn't premium have ethanol in it too? ....?

Not where I buy fuel. It's listed right on the pump:
regular has "up to" 10% ethanol.
mid-grade has "up to" 5% ethanol.
premium has "no" ethanol.

It's easy to test and see for yourself.

Place 1" of water in a tall straight sided glass jar or clear plastic bottle, and make a mark at that level. Make another mark 5" above the first mark. Fill with gasoline to the upper mark and shake to mix the water and gasoline, then let it sit until the two fluids completely separate. For every tenth of an inch the division between the gas and water has risen above the 1" mark, there is 2% ethanol in the gasoline. For more accuracy use a taller container for a 10" sample and 1/10" is then 1%.