Chicagoland Rust Prevention

I have a 2023 suburban(i know not a silverado). I have a local shop that does fluid film application for $389 the first application and then $80 for every application after per year. I've seen mixed reviews with people saying fluid film tends to eat away at the gm factory wax undercoating or cause it to bubble up. Some have also said it could void the warranty. Is wool wax a better option? Others swear that I should just get my undercarriage washed frequently during the winter. Any opinions or experiences with the above?

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The factory undercoating is junk and doesnt last that long anyway. Fluid film and wool wax are both common ones you hear about online. The application is as important as the product. Especially for underneath it needs to be something thin enough that it'll sink in and travel a bit but thick enough to stay in place and not wear off quickly.

Unless you do an extremely painstakingly thorough undercarriage washing,
there's always a possibility that the salts might migrate to places that cannot be easily rinsed out.

I know this is an unpopular suggestion, but I attach a piece of coroplast under my Tahoe every winter -
with cut-outs for front wheel steering movement.
(Fluid film / wool wax applications are not easy to find in NY / NJ / CT / PA.)
I dare anyone to do better for $20 (you'd have to find a cheaper big@$$ piece of coroplast).

Man, gotta say I've never even heard of fluid film or wool wax. (Might be why I eventually had rust bubble up in my old '09 Tahoe's passenger-side rear wheel well lip...)

Yea the factory coating is complete garbage…scrapes right off to bare metal with the back side of a fingernail. Not sure there is much recourse on the warranty, but be rest assured the junk will be chipped off and rusting just a few short years regardless of any extra treatment that may screw up the warranty.

Marky Dissod said:

Unless you do an extremely painstakingly thorough undercarriage washing,
there's always a possibility that the salts might migrate to places that cannot be easily rinsed out.

I know this is an unpopular suggestion, but I attach a piece of coroplast under my Tahoe every winter -
with cut-outs for front wheel steering movement. (Fluid film / wool wax applications are not easy to find in NY / NJ / CT / PA.)
I dare anyone to do better for $20 (you'd have to find a cheaper big@$$ pice of coroplast).

Click to expand...

okay…i gotta see this lol

I have been spraying fluid film on my truck just before winter since i bought it in 2016 (its a ram, so dosnt have that ****** undercoating stuff from the factory). FF works vey well in hidden areas where they do not get constant spray from the tires (inside rocker panels, doors, tailgates, fenders etc.). I usually spray the entire undercarriage anyway while im doing it, but it dosnt last very long.

The important places to get are the crevices in between the body panels that hold salt/debris. Like the rocker panels and doors and rear lift gates and such. Contrary to popular belief, vehicle bodys dont rust from wear and chips on the exterior painted finishes…they rust from inside the body panels. That is where you gotta get the product.

olyelr said:

Contrary to popular belief, vehicle bodys dont rust from wear and chips on the exterior painted finishes…they rust from inside the body panels. That is where you gotta get the product.

Click to expand...

X2

I do 2 fluid film applications a year. One in the spring and one in the fall. The underbody washes I don't think would do a very good job of spraying and rinsing out the holes in the frame or the body where the rust is going to initially form before it eats through and you notice it on the exterior.

Marky Dissod said:

I know this is an unpopular suggestion, but I attach a piece of coroplast under my Tahoe every winter -
with cut-outs for front wheel steering movement.
(Fluid film / wool wax applications are not easy to find in NY / NJ / CT / PA.)
I dare anyone to do better for $20 (you'd have to find a cheaper big@$$ piece of coroplast).

Click to expand...

olyelr said:

okay ... i gotta see this lol

Click to expand...

Although a pic is worth a thousand words, I'm bad at pics.
It's like a buffet sneeze guard - makes it harder (almost impossible) for the road to sneeze on my undercarriage.
Actually, forgot to mention, a dozen beer bottle tops are extremely helpful, and so much cheaper than washers.

I only paid a few thousand to make someone else's '02 Z71 mine.
It makes a lot of sense to spend more money to do a better job protecting a newer vehicle's L0INS,
but like I said, I'm looking for a cheaper coroplast source ...

X3 here.

I live in WI, and frequently drive in Chitcago area road salt. I've done fluid film for many years and IT WORKS! It's the only thing (along with wool wax) that creeps without drying. $389 for initial and $89 for yearly touch ups is a great price!

I bought my own professional gun about 15 years ago and have applied numerous gallons of fluid film over the years. The last vehicle I took care of with it, put tons of miles on, and then sold was a 2007 Yukon Denali. It looked brand new still underneath, the buyer was amazed.

Done properly, you should have a good, thick residue on the entire frame, underbody, inner fenders, doors, etc. A good shop will pull body plugs for access, make sure the clamps around your rear A/C lines are coated well, brake lines, fuel lines, etc.

You will need to have a touch up yearly on the frame rails, most everything else will repel the water and salt. I rarely have to refresh doors, fenders, or underbody. I will CAUTION you against excessive washing. The harsh soaps can dissolve the coating. STAY away from undercarriage washes as well because all they do is blow the crap UP into the body and do more harm. Not to mention a lot of washes by us are required to recycle water, which ends up washing your vehicle in salt water.

Sorry for the long winded explanation, but after working on rusty chit for years in shops, I have a real passion for keeping stuff nice. Not to mention the value in it based on new car prices.