Hi,   I am wondering if this product is a good option to slow down the spread of rust inside the lip under the car door.  There is a seam where the rocker panel meets the frame where rust is emerging, and is not accessible without removal.  I would like to spray the coater in there using a nozzle, in the hopes of sealing it up enough to slow things down.   An image of where I would be applying it is here (not my car, but same location): Thanks!

The Cavity Coater is ideal (http://www.kbs-coatings.com/Cavity-Coater.html). The advantage of Cavity Coater is that it requires minimal prep and still gets excellent adhesion. We even have the Cavity Wand (http://www.kbs-coatings.com/Cavity-Wand-18.html) which would allow you to get the Cavity Coater in to this tight spot. So, we would suggest the Cavity Coater as being ideal for this applicaion. As always, please let us know if you have any additional questions.  

I have a similar question. I have a 1997 F-250 I use only in my yard for a plow truck that runs and plows so nicely, I'd like to protect it for many years to come. The bottom of the doors and the cab corners are rusting, so I would like to know what you think I should do to stop/prevent spreading. Is it always best to cut the rust out with a die grinder first, then treat the remaining metal, or is that not really necessary? This isn't a show truck or anything...just want it to last. Thanks in advance! TommyZ

Treat the rusty areas with the KBS 3 Step System (http://www.kbs-coatings.com/kbs-three-step-system.html) and then apply your touch-up paint over the RustSeal.  That should work great for you.