>>Speaking of octane, has anyone had experience with mixing leaded
>>regular and unleaded premium? The theory is that the result should have
>>higher octane than the unleaded rating.
>I heard this rumor many years ago and I asked a couple of friends
>fathers (both of them have phd's in chemistry) and they both gave me
>the same answer. The final octane level would be the average of
>the two. So, if you put in 5 gal of 92 octane and 5 gal of 88
>octane, you would have 10 gal of 90 octane.
>However, these chemists, were not in the petrol-chemical industry.
>It could be possible (very remotely) that the lead in the regular
>and what ever they add to the unleaded for higher octane react to
>create a higher octane level.
>Has anyone heard of any tests to prove or or disprove the idea?
> Larry Schwarcz
I recall an article in Motor Trend in 1985 that discussed this exact
idea. Such a mixing of unleaded high-octane gasoline and leaded
gasoline resulted in a higher octane than either due to the fact that
lead acts as an octane booster; back in the late 70s and early 80s when
leaded gasoline contained a significant amount of lead, this served to
add lead to the unleaded gasoline, boosting the octane yet further.
However, with the dereasing amoungs of lead in leaded gasoline, this
effect had just reached "break-even" point in 1985. (Meaning that
adding leaded gasoline to high-octane unleaded left you with the
high-octane figure -- assuming a 1 to 1 mix ratio.) This was a little
cheaper at the time. However, with still less lead in unleaded
gasoline (as Bill Sohl pointed out) this no longer works, and the
effect is that more towards averaging the octanes of the leaded and unleaded
fuels.
Ken Streeter
oneway@athena.mti.edu
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