I own an 2002 Ford F150 XLT with engine recently replaced. The mechanic related I should put four bottles of rubbing alcohol in the gas tank because the gas was old. Is that the right thing or please provide guidance.

 

If I had a new engine..... I would run it only on new gas during break in... But that's me.
Less critical if it's a used engine..... But I might still not want to run it on old crappy gas.