What are the opinions on undercoating a new vehicle and how often it should be repeated. When I bought my last new truck in 2010 the service manager at my dealership advised me not to have it done because sometimes the door drains get blocked and water that enters at the windows can't get out. I had it done at Krown anyway. My doors didn't rust out, but my fender well edges did. Only had it done about twice. Should it be a full undercoating job or just an oil spray underneath? Should aluminum body be treated differently than steel?

 

This is what I would use: RP-342

 

My opinion is to have it Krown sprayed once a year and NEVER use a product that covers the metal.

 

Krown, or fluid film, seems like the best option with no risk. the "permement" coatings can trap moisture.