I use motorcycle chain lube. It works great and its a spray can type application.

 

Here is what I did, its a more permanent solution that wont wash off. First pry your middle leaf down away from the top leaf, then cut approx 4" x 4" strips of an old bicycle tube, and stick them between the end of the second spring and the top spring. Had them in there over a year now and not a single squeak since

 

That is what everyone does here too bro, funny stuff but works great. Meh, not in the mood to do all that but it's a nice tip!

 

Worked perfect for me! took maybe 5 minutes from start to finish