Is Ethanol based gas that bad for the engine?

[ambush276]

I am curious about using gas in an m117 engine. Almost all gas stations (especially here in california) have ethanol in their gas and I have been told by some friends that this is really bad for the engine and fuel system and should not be used. I am possibly getting an m117 engine car (w108 4.5) but i am 99% sure all stations around me have some ethanol in their gas. Is it really that bad? Is there an additive i can put in to help equalize the affect of ethanol (not sure what it is) on these older engines). What does it do that is so terrible for the engine and is there anything i can do to negate this affect.

Thanks !

[Coolvibes]

I'm not sure if it's bad for the engine, but a mechanic told me it's bad for the rubber and gaskets components in carburetors. I use REC 90.

[Graham]

I have used gas with 5-10% ethanol in my M117 powered car with Djet (same as 108) for many years. No problems, but it is a good idea to change out all the rubber fuel lines from tank to engine. And especially the fuel injection rail tubing and the 7.5mm ID injector connectors. Need to use the proper OE tubing or Contitech equivalent.

In carburetors with float valves for example, there is a problem. I have several outboards as well as garden tools. Learned to run them after use until they use up all the fuel in the float chamber and stop. Otherwise the needle shut off valve (with rubber tip seal) sticks to seat and won't let fresh fuel in.

[97 SL320]

Ethanol leans out the fuel mixture so on a system without a O2 sensor you could be running too lean if the engine was already on the lean side. Otherwise it won't damage the engine mechanicals.

It can damage fuel pump commutators or anything with a copper content like brass especially if the car sits too long without being used. ( Like 6 months + )

[Idle]

There is an additive you can get that is supposed to cushion the valve. This is what the lead once did among other things.

A friend of mine has an early 70's Chevy Suburban. He always treats his gas with this stuff and has for years. He has never had any problem outside the normal wear and tear.

[gmog220d]

I read a little about additives, and you generally want to avoid using an additive that has alcohol in it. The older engines supposedly tolerate alcohol to a point, and if you run an additive that adds more you can reach a tipping point and end up doing more harm than good. Lots of information/discussion on the interwebs about this issue.

[muleears]

I live out in the country in an agricultural area. There are gas stations here that sell PURE gasoline, no ethanol. Apparently farmers and/or farm equipment like the pure stuff. The one near me is the Southern States chain. You might be able to find something similar.

[TroutMD]

Try the Pure Gas app or website, it will locate ethanol free nearest to you where you live.

Everything I have read indicate ethanol free is preferable to use in these cars.

[ambush276]

it's in california... bay area... GL finding non ethanol gas hahahah.

I can tune the EFI differently to compensate? What would be an additive that you would recommend?

Thanks.

[muleears]

Originally Posted by ambush276

What would be an additive that you would recommend?

Thanks.

I use STA-BIL, its a gas stabilizer usually used for storage but they make an additive to counteract ethanol too.

[Graham]

Originally Posted by ambush276

it's in california... bay area... GL finding non ethanol gas hahahah.

I can tune the EFI differently to compensate? What would be an additive that you would recommend?

Thanks.

You are looking for a solution to a non-existing problem. An M117 Djet will run and be fine on regular gas with 5-10% ethanol. This based on 20+ years doing just that including 4-6 months of winter storage each year. Mixture specs have a wide range so no need to make any changes in tuning. Full time wideband AFR readout on my M117 shows no discernible difference when using 10% ethanol or ethanol free fuel. As posted before, spec for fuel hoses has changed to better handle ethanol and those should be upgraded all way from tank to injectors (and back)