Teflon tape used on pipes that carry gasoline and or diesel fuel.
From another web site....
White tape is single density and intended for water pipes of 3/8 of an inch or less. It can sometimes be found in a silver color to match the pipes.
Red tape is triple density, for pipes one-half inch to 2 inches in diameter. It is designed for pipes with larger joints, such as water distribution pipes. Note that the container is red, but the tape itself looks pink.
Yellow tape is double density, and designed for gas and fuel lines.
Green tape is grease and oil free, and designed for pipes carrying oxygen.
Even if you are on the right track, you will still get run over if you just sit there.