Cold Weather Performance issues from new owner of an '84 318

[M10Power]

Two questions:
Is higher-octane fuel harmful and/or ill-advised for an M10, and does winter weather factor affect higher octane gas at all?
Does anyone experience what I'd consider a LOT of white exhaust gas at startup/warmup in cold weather? It looks like steam from the driver's seat - as I accelerate while the motor is still cold it really comes out in volume, and looks terrible. But once the temp gauge hits the 12 o'clock position, there is no visible gas. And it's never bluish smoke like oil is burning.


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[TobyB]

An m10 will be fine on 87.

Sniff what's coming out- if it doesn't smell sweet like coolant, you are experiencing
normal e30 condensation.

t

[Matt-B]

that is what every car does when its cold and warms up...if its sold white headgasket, if like smoke from a fire look, just moisture


and temperature really wont affect gas, unless your way in the negative. I also dont think running 92 octane is harmful, i only run it or premium in my cars

[TobyB]

Agreed that temperature doesn't affect the gas- in old cars tuned right to the hairy edge,
colder air needed a bit more fuel, since the air was denser. The M10 is not that fussy,
and anyway, it's temperature compensated in the E30.

A long time ago, I discovered that higher octane fuels in engines not designed to burn it
reduced my fuel economy. Sometimes noticeably. So I stopped doing that, since it cost
twice. Even the Pro3 car (stock chip) makes more power on 87.
So the cars that want it (either by sticker or by rattling) get higher octane.
But everything with a stock M10 gets 87, here.

Jus' me.

t

[Eta power]

Two questions:
Is higher-octane fuel harmful and/or ill-advised for an M10, and does winter weather factor affect higher octane gas at all?
Does anyone experience what I'd consider a LOT of white exhaust gas at startup/warmup in cold weather? It looks like steam from the driver's seat - as I accelerate while the motor is still cold it really comes out in volume, and looks terrible. But once the temp gauge hits the 12 o'clock position, there is no visible gas. And it's never bluish smoke like oil is burning.


Sent from my iPhone using Tapatalk

For every gallon of gasoline burned, a gallon of water is created.

When the engine is cold, fuel does not atomize as well as when the engine is hot. In order to compensate for this, engines run rich when cold.

The exhaust will also be cold at this point, meaning more water vapor reaches the tip as vapor and not steam (real steam is invisible, what most people call "steam" is water vapor, a.k.a. a cloud)

These things combined mean that you will get white "smoke" when cold. This seems to get worse the older and more worn the car is. My M10 car does this a fair amount and it runs like a raped ape.

As Matt said, if the engine is burning coolant, you will get billowing white smoke that will hang in the air (regardless of engine temp). This smoke is thicker than the could of water vapor you normally get at warmup. It will also smell sweet, because most common coolant contains Glycol, a sugar.

[M10Power]

Great details!

Thanks for the thorough reply. Car definitely runs rich when cold - I've just been surprised at the duration of the fog bank that it creates when driving to work. Looks like some kind of feature 007 would use. But absolutely the cloud dissipates eventually.

I'll give 87 a go on my next tank.