The fuel cells that have a bladder in them will also have a date stamped on them beyond which they should not be used because the material loses some of its impact absorbing qualities. All the sanctioning bodies in racing adhere to the date for usage and it is an item checked in tech before they are signed off. As a side note, I have used small pieces of fuel cell foam inside the tall breather tubes to prevent
oil from being blown out the breather caps and valve covers. Works well. Just be sure it can't slide down into the rocker assembly.
..........Rick
