I’ve owned 2 Gen2s, the 2020 I have seems to have a better coating on frame/tow hooks thicker coat & more like a semi-gloss, the 2018 had a matte finish on frame/tow hooks similar to what’s on the exhaust tips.
The 2018 had zero rust when I got it, the 2020 had only a couple small spots around diff- if you look around may find a thread where I posted some pics of the process/results but in a nut shell this is how I treated undercarriage/engine bay on both of em
Pressure wash undercarriage etc, really good, let it dry and/or used compressed air to speed process, timed this when I knew would have stretch of warm/dry weather
Once dry I used paper shopping bags/painters tape/plastic wrap to protect inside of wheels & fox shocks, put some cardboard underneath to absorb drips/overspray & first scuffed up
The rear diff/axle w/ sandpaper & a wire brush, wiped down w/ tack cloth, then gave 2 coats of rustoleum semi-gloss.
Gave it either 6 hrs or overnight to dry
Then went to town on everything underneath w/ cans of Amsoil HDMP- probably equivalent of 3 coats worth, used 6-7 cans lol. Now, after the first coat starts to set you start getting a buildup & while it’s kinda tacky to the touch it’s more like a beeswax consistency- doesn’t attract dirt/dust like fluid film, just rinsing w/ a garden hose typically removes that stuff. What you wind up w/ is really a semi-permanent coating- diffs/t-case/tranny/leaf springs/every nut/bolt/hanger gets covered, you don’t want it to get on shocks b/c on anything that isn’t black the Amsoil HDMP leaves a golden yellow color. It doesn’t seem to effect the black parts as much in terms of color, w/ the heavy coats I put on there’s a few spots like drips or whatever that sort have a yellow tint if you look up close but for the most part this stuff makes black metal blacker. Side note- spray some on a microfiber rag & use to clean up exhaust tips/tow hooks, works great for that.
On the top side of the engine bay & on the fox shocks I used Yamashield - this stuff goes on clear & can be sprayed on anything- rubber/plastic/electrical doesn’t matter, not as permanent a coat as the Amsoil so would touch up every year. This is a yamalube product made for marine application- I douse the hell outta my wave runners with it the intake grate/impeller & engine, theres nothing better for bare aluminum in particular. Impregnates the metal & forms some chemical bond - very good on engine block