Rinse undercarraige in winter or no?

If I had to power under spray my wife I might be rethinking a few things.

 

It won't wash all the fluid flim away, but it will leave many areas exposed to rust. I ran my tundra through just 1 car wash, and a couple weeks later much of the frame was showing surface rust.

 

I was agreeing with you.

That means it was rusted before you sprayed. You need to start with FF from before your first winter and reapply at least yearly as required. I get my truck's Rust Check sprayed every year, and the undercarriage look amazing (after I powerwash all the dirt struck ontop of the undercoating ), even after 8-10 years.

 

Yep, it had some rust spotted areas throughout the frame from waiting till the 2nd year to start with fluid flim. What i was surprised was how fast it became rustier where the fluid flim had washed away. It got a little worse every year in the spring as the fluid flim i put on in the fall would get washed away on wet salty roads. When i used cosmoline on my tacoma it hasn't happened. Been good for 2 years now without reapplying. With fluid flim you had do do it every fall, or twice a year for the best protection.

 

So in the 80s BMW would cosmoline the engine bays of their cars when they shipped them. It was up to the dealers to clean it off before sale, many didnt. 256,000 miles and 32 years later my 1991 BMW still has cosmoline in the engine bay and all over the engine.

 

I wouldn't if I used an underbody coating. Work smart. Now since I don't coat I bought a pressure washer and every week I clean the undercarriage.

 

I try to spray mine off after every bout of snow and salt... that is if it warms up enough to do so, the roads get dry and the weather is not expected to crap on us again for a week or so. I just crawl under with my hose and nozzle... also get the wheel wells and brakes and such. Not too anal about it, just try to do what I can.

 

Why?

 

Salt country here. i thought i was smart and powerwashed my old 4runner frame all winter instead of oil spray. It turned to swiss cheese after a couple years except for the places the engine leaked

 

Good to know this. I guess if you want true peace of mind, might as well get coating every year. Less of a hassle too

 

Its tough stuff, but mineral sprits, or gas will take it right off.

 

It's likely that the water pressure will push salt, dirt, & debris further into barely accessible crevices of the unprotected frame, providing a fertile breeding ground for rust & actually exacerbating corrosion.

 

There is some forum-hype happening with this stuff. No pun intended but every word we all say here should be taken with a grain of salt. I see dozens of 90s Tacoma’s and Toyota Pickups around here every day, most of whom have never cleaned or fluid filmed their frames, and didn’t need the frame recall. YMMV should be mandatory at the end of every frame rust post haha!

Most of the frame is C channel so it rinses well. Only a few cross members are fully boxed, even then they have drain holes as far as I can see. If those are untreated inside, I agree that’s bad. But I don’t believe that spraying the undercarriage gets water anywhere that driving on a wet salted road wouldn’t. And plus, if they’re such hard to reach areas, your fluid film aerosol can won’t get that product there either.

We don’t have have salt in the air here in the mountains, and only have a few storms worth of mag chloride solution each winter. I guess I’m taking my chances!

YMMV

 

Nobody ever thinks of this stuff but you need to consider that if the Govt. and most of the airlines along with oil rigs in the North Sea, Railroads, etc use this it might be worth your time to investigate. It is and has been in wide use in Europe for years but here in the states is still largely unknown. We used it to spray the wheel wells on Boeing aircraft, Airbus and you can imagine the hostile environment that must be. We also used it in the cargo compartments beneath the floors because on international flights the ramp people urinate in the cargoes and is highly corrosive. After seeing what it can do I bought it for my cars. It goes on almost clear so you can see what is happening to the metal underneath. It dries to a semi hard wax like consistency and needs a solvent wash to remove. It stays put

 

I heavily coat everything underneath each fall with Fluid Film. I do not spray down my frame and attached suspension parts/underbody here in Marylandistan during the winter. My technique seems to be producing, I still have ZERO rust anywhere underneath during the spring/summer months when I do wash it down.

 

You do you, Jackie Moon!

 

Mine is 2016. We have had snow since Nov 16, about 30 inches since then. Roads covered in snow, salt and sand for the last 2 months now. I have washed my truck once in the last 3 months.

That was in my driveway with a pressure washer just so I could get inside the wheelwells, and underside and clean it up a bit in the nooks and crannys. Did not wash the outside of the truck, no point since the roads are crap and back to dirty the next day. My last full wash was first week of November.

I think as one guy said, don’t overthink it. This is my 4th 4x4 in the last 35 years, and each would get maybe 2 washings on the underside over the worse 3 months of each winter. Despite 30+ hardcore offroad trips each year on bad trails in BC, and snowy winters, all of my trucks looked pretty good for many years. Wax them twice per year, once before winter and once after, and it works pretty well. Never had any issues with rust even on my old 86 F150 which took a heavy beating for 13 years. We have had 3 bad winters since I got my Taco, and zero rust on the underside and I check that several times per year due to my undercarriage taking a beating off road.

Truck has looked like this every day for 3 months now, and the same the previous 2 winters. No mud since it is just snow salt and sand. Looks a lot worse in person, in that pic it looks like it just rolled off the showroom floor. The orange masks the dirt pretty good. Best thing is you can’t see the license plate on the back so its great for getaways. Still, no rust on the underside and nothing special done, just the original coating when new, and that rust treatment the dealer put on for the frame issue.

 

I'll do the same. Late fall I'll pressure wash and let it dry a few days then heavy fluid film everything. Then during salt season I'll wash the topsides but leave the underside basically alone. Once I feel the salt is gone I'll get out the gutter cleaner and go to town on the underside to get as much salt and muck out that I can. The waxy feeling remains on most of the metal. Been doing this since I took delivery in 2016. The only rust I have is on the front of my A arms where they get blasted. I'll probably POR 15 those in the summer.