21' GMC 2500 Sierra Denali (latest pickup)

SupremeAboriginal · Jun 12, 2026

Just bought a 21' Sierra Denali 2500. Im new to diesel trucks...i got the truck for basically a $10,000 discount compared to others with the same mileage/year/trim. The only catch is...it has a good amount of undercarriage surface rust because it came from Canada. Nothing too bad (as of yet) but i do want to take my time and do my research on how to rid the rust and protect it from getting rusty in the future. If anyone has any suggestions...please, im all ears. Thanks. Nonetheless, its an excellent truck!

Jus Cruisin · Jun 12, 2026

Spray the undercarriage with Fluid Film.. I've used it on rusty looking F150 rear axles. From rusty to black in about a week.

olyelr · Jun 18, 2026

Gm, for whatever reason, does not paint there frames. They use this stupid ass black pliable/rubbery product to coat it. Just drive through any dealership and reach under a brand new one…you can scrape that shit off with a light fingernail scrape right down to bare metal. The dumbest shit ive ever seen.

From what i have read online, most undercoating type products should not be applied to that type of factory coating.

Ive been spraying fluid film on my ‘16 Ram since new…she still looks pretty good after its tenth michigan winter.

21' GMC 2500 Sierra Denali (latest pickup)

SupremeAboriginal

TYF Newbie

Jus Cruisin

Member

olyelr

Full Access Member

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