WD-40 is too thin. It would work tempararily. Spraying used engine oil would be better. I've been told that some people use some on the bottom, inside of the doors as well. It is supposed to be effective...

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Sgtsandman's Work in Progress
2011 Ranger XLT, 4X4, 4 door Super Cab. 4.0L, 5 Speed M50D-R1HD, 3.73:1, 8.8" open differential, Jason Pace cap
2019 Ford Ranger STX FX4, Super Crew, 2.3L Ecoboost, 10 speed automatic, 3.73:1 with rear locker, Leer 100XR cap