Just my .02 cents worth but I'm pretty sure nearly all of the new cars and trucks coming out have a coat of crap on the bottom of them now to help prevent rusting. I'm sure you could make it better but wouldn't you have to scrape and clean all that stuff off first? Most of the ones I've seen that have it, it's like a film of thick nearly dry grease.
True but I have seen some newer Chevys and GMCs with alot of frame and chassis surface rust. Having a little more protection is a must if you live near the ocean or somewhere where it snows and they use road salt. I touched my frame up ( it had already been undercoated ) but the road salt still killed my cab corners. Im pissed, the damn thing was perfect and now the cab corners are blistering up.
99' Silverado 5.3 4X4
Modified Predator 93 tune: TQM @ 40%, injector slope bumped up 4 levels,
125 MPH top speed, 5500 RPM limit,
TBS, 180 thermostat, 4" CAI with 9x6" element,
Bypass and De screen performed,
AVG: 16 MPG City, 20 MPG Highway
If in an area that causes rust...get her undercoated. The wax dipping done at the factory is not enough. And I think they can blow it on right over the wax. My dad had his 04 done. I didn`t do my 05 since I won`t have it long enough to worry about it.