Anyone here undercoat truck with Fluidfilm/Woolwax/Surface Shield?

JustinB60 · Dec 20, 2021

Just picked up a 2022 AT4 with 3.0 diesel and I want to undercoat my truck as I live on a dirt road and in Michigan, this means the truck will get copious amounts of salt/sodium chloride/brine/etc on it both on the dirt roads after resurfacing as well as all winter long on dirt and paved roads. I've been doing a lot of research into undercoating and it sounds like it is widely known now that hard undercoating, such as rubber undercoating products, lock in moisture and cause more harm than good and the new thing is "oil undercoating" which usually means Lanolin-based coating.

If anyone here has applied Fluid Film, WoolWax, or Blaster Surface Shield to their trucks please let me know if you applied over factory wax and if it caused factory wax to come off or if the wax stayed on fine. I'm also looking for any tips on particular nooks and crannies to keep an eye out for. Did anyone apply it to the drain holes in door? If so any rubber door seal swelling afterwards? Any spots I should avoid applying this to underside of vehicle?

Here's a photo of the new truck:

chaos · Dec 22, 2021

want to follow to see what you do- mostly because I need to do the same! I'll probably use Blaster Surface Shield. Based on this YouTube video it seemed to be the best?

Caprisun · Dec 24, 2021

I was looking into doing something of the sort. Amsoil makes/made one that was very highly rated but totally out of stock. Stopped researching it after that.

JustinB60 · Dec 24, 2021

Well I ended up going with WoolWax for now. Removed all the wheel well liners and coated behind them as well as inside rockers and around top side of inner fenders as well as a lot of seams underneath. I didn’t apply anything on top of the wax frame for now as Woolwax website says that it can cause the wax to degrade. I won’t be driving much over the next few months so I figure I’ll wait to see if anyone tests out Surface Shield on the GM wax frames, if that product is good to go on wax frames I’ll pull the truck back into garage and coat the frame with it. I had bought a gallon of Woolwax, fluid film, and a gallon of Surface Shield and by far the fluid film smelled the worst to me. I plan to only use the other two products on my vehicles, maybe I’ll use the surface shield on my ATV and tractors.

Pb82 Ronin · Dec 24, 2021

Isn't that the factory undercoating? There is already some nasty stuff underneath it. Don't believe me? Go underneath your truck and touch all the black stuff with your bare hands. Then enjoy spending the next 30 minutes or so washing that crap off..

JustinB60 · Dec 24, 2021

Pb82 Ronin said:
Isn't that the factory undercoating? There is already some nasty stuff underneath it. Don't believe me? Go underneath your truck and touch all the black stuff with your bare hands. Then enjoy spending the next 30 minutes or so washing that crap off..

The factory “rust proofing” is the wax on the frame that I talked about not applying anything on top of…. That’s what gets on your hands and is hard to wash off.

chaos · Dec 25, 2021

Thanks for the pointers. I went ahead and ordered a gallon of surface shield. I'll keep away from the frame and put it every where else. I also have a Jeep that needs some rust proofing to try and limit the amount it gets worse. No wax frame covering on that though.

What's the consensus on inside of the frame? I assume the wax stuff is on the inside as well, so no need to coat?

JustinB60 · Dec 25, 2021

chaos said:
Thanks for the pointers. I went ahead and ordered a gallon of surface shield. I'll keep away from the frame and put it every where else. I also have a Jeep that needs some rust proofing to try and limit the amount it gets worse. No wax frame covering on that though.

What's the consensus on inside of the frame? I assume the wax stuff is on the inside as well, so no need to coat?

To me it looked like there was wax inside the frame as well so I skipped it, let me know if you can see inside there and find it’s not wax coated! Another couple pointers: lay down a tarp or cardboard under truck before you spray if you don’t want it in cement. If you want to remove wheelwell liners then just know fronts come off and back on easy even with wheels still on but the rears i suggest you remove wheels, they’re a PITA. If it’s colder then 70 outside consider warming up the bottles (or gallon) of undercoat before spraying it on. Lighting is key (good headlamp plus extra lights) as well as lifting truck a little to give yourself space, a lift would have made it so much easier on me.
One last thing, Woolwax looks and feels and acts like car wax when you overspray on paint but because the surface shield dries out a little more to become a more durable harder barrier I would suggest cleaning off overspray on the paint right after you finish spraying it. Let me know how it goes!

Abell34 · Dec 31, 2021

Interesting info here. Just bought a 2021 at4 with the 6.2 last night. I have had success using a local detail shop to oil spray my previous vehicles. I honestly didnt know there was much difference in products. But i havent had a wax coated frame to consider until now. They recommend recoating every 18 months or so i believe to maintain the no rust gaurantee. Its around 250 bucks or so for the full service option. 150ish for undercoating only. Stinks for a day or two when the exhaust gets hot but seems to work good. My last truck i let go 3 years after the first coating and it was just starting to get little surface rust spots on the frame.