[urq] Acetone fuel additive, your opinion please

[Mike Fitton]

I looked into this pretty seriously several months ago, and my friend 
tried it out for a little while in his Subaru (2.5RS).  Acetone is a 
ketone, so it lowers the surface tension of petroleum products like 
gasoline and diesel, some more than others of course.  The idea is that 
lowering the surface tension a little helps the fuel to atomize better 
and in turn combust more completely.  Since it's in such a miniscule 
volume, its chemical effects on combustion are pretty minimal.  Where I 
live, there are no smog tests.  I'd like to run some emissions tests in 
a smogged city/state on a fully tuned and catalyzed car to see exactly 
how much it changes things.

I think my friend saw about 3-4mpg in the short term (high 20s to low 
30s), and I think that engine's in desperate need of a tuneup.  Whether 
that means a nicer engine would see greater or lesser gains is hard to 
say.  I need to get him to try it on his Miata...that's in much better 
shape.

I have seen reports of cleaner valves and spark plugs with the use of 
acetone, but I suspect that's more a result of the slightly higher 
combustion temperatures than any chemical action.  As far as long term 
side-effects...well, I got a D in chemistry.  Things to consider are how 
fuel system parts are going to react to a ketone.  Things like...what 
happens to rubber o-rings, what happens to metal hardlines after 100k 
miles?  I still haven't found any documented evidence either way, so 
it's still a little questionable.  I've seen a lot of acetone crusaders 
and not many leaning the other way, but that doesn't really mean 
anything conclusive.  We all know there's plenty of snake oil out there...

-Cheers!
Mike

Maurits Jonkergouw wrote:
> Has anybody ever used Acetone as a fuel additive (max. 0.3%) in the past (or 
> present) and what are the possible short / long-term effects? Does it lean 
> out the mixture? Does it 'clean' any carbon residue way too much and thus 
> better not used with old engines such as ours?
>
> Regards,
> Maurits
>
> 1986 quattro GV
> 1985 Coupe GT KV
> 1982 Coupe GL DD 
>
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