i never used the marine clean, probably cuz when i used the por we were taking the entire car apart and a lot of the parts got sandblasted to clean them up, but the metal ready is a must, it prepaires the metal (with a acid etching) to accept the por-15,if i remember correctly, it was in a spray bottle and went a long way, there was a tip posted here not too long ago about putting 2 small holes in the top of the can(never taking off the top) 1 small hole for a vent ,,,,the other to pour out the por-15 into a small jar,,,then put screws into the holes,,this way the can will last you quite some time,,,and this stuff does go a long way,,,you'll be suprised how far a little will go!!!---also you probably already know this,, but while were on the subject,,, it dries best in huminity so if its cold where your doing it ,,it may take some time to dry.. my undercarrage is done with the stuff,,tie rod ends are pored and then a top coat of metal mask,, makes them look like bare metal,,,then i went over that with glisten p.c. for a rock hard clear coat