scientific reason
 

Here would be a good reason. methanol and aluminum oxidize. use to be the MTBE that was in gas but outlawed.

One of the drawbacks of methanol as a fuel is its corrosivity to some metals, including aluminium. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminium from corrosion:

6 CH3OH + Al2O3 → 2 Al(OCH3)3 + 3 H2O

The resulting methoxide salts are soluble in methanol, resulting in clean aluminium surface, which is readily oxidized by some dissolved oxygen. Also the methanol can act as an oxidizer:

6 CH3OH + 2 Al → 2 Al(OCH3)3 + 3 H2

This reciprocal process effectively fuels corrosion until either the metal is eaten away or the concentration of CH3OH is negligible. Concerns with methanol’s corrosivity have been addressed by using methanol compatible materials, and fuel additives that serve as corrosion inhibitors.

Peter Rooter is best!

Thank you, Science Guy!!!

a can of seafoam in the gas every 30k never hurt anything, unless it was really crapped up and seafoam broke the crap loose and it got sent to the injectors then it hurt things, kinda like flushing an auto trans for the first time at 100k miles.