This is for a 2000 Nissan Altima.

Some one told me that her husband accidentally pumped one gallon of diesel
fuel, realized the mistake, then filled the gas tank with 12.6 gallons of
regular gas. They then drove approximately 60 miles to get home.

I don't know the capacity of the gas tank, just approximate. I have a Haynes
book on the Nissan Altima for the correct year, but the word "Capacities"
does not exist in the index and the only table for "Capacities" that I have
been able to find is for the engine and transaxle.

Will this hurt the engine?

Thanks,

Ken