# Rust Proofing undercarriage prep



## 97S104x4 (Dec 31, 2009)

So I want to rust proof my undercarriage and frame with motor oil. Now how do you guys prep or clean the undercarriage before applying oil, fluid film etc etc? Will just hosing it down and letting it dry be enough? Also do you guys wait a while before you drive after applying motor oil or fluid film or get it and go right away? 

The truck is a 2015 2500hd


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## darryl g (Jan 30, 2010)

Not sure why anyone would spray something like motor oil under their truck. Do you really want free-flowing oil like that dripping from your undercarriage?

In any case I use fluid film and just brush/blow off any dirt and grit that I can off.


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## ScubaSteve728 (Jan 17, 2012)

honestly a 2015 should not need fluid film yet still should have plenty of stock rustproofing still. 
if you do wanna FF it power wash underneath


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## TMLGC (Sep 22, 2013)

I do it in the late summer or early fall. Spray around underneath with a hose, let it dry a day or 2. I use used diesel oil with a spray bottle and brush. I do let it sit overnight. I use a can or 2 of FF as well in the doors under hood ect.


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## allagashpm (Sep 29, 2012)

TMLGC said:


> I do it in the late summer or early fall. Spray around underneath with a hose, let it dry a day or 2. I use used diesel oil with a spray bottle and brush. I do let it sit overnight. I use a can or 2 of FF as well in the doors under hood ect.


I have the same method but use bar oil.
I park over a big tarp and let it sit for a day or so then zip down a gravel road to kind of seal it in. 
Make sure if you have any work to do on it you do it before. Kinda messy to work under there for a couple weeks lol


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## Hysert (Dec 16, 2009)

OP do not use motor oil on your undercarriage! The additives and fuel that gets mixed in the the engine oil will break down your polyurethane and rubber parts! ie... bushing/gromets/seals etc... just spend the $125 and get it properly done by a specialist in the business or by a pale of FF and a airless sprayer and do it your self!! It's


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## 97S104x4 (Dec 31, 2009)

You cannot use fluid film on the new chevy frames, it softens the factory undercoating up. Fluid film was going to be my first choice until I found out it has a bad reaction to the factory undercoating.


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## darryl g (Jan 30, 2010)

I see. I know people do this all the time, spraying oil on their cars/trucks. But I can't help but ask you if you're sure you really want to goop up a truck that new, attracting dirt and grit, motor oil all over and dripping wherever you park for a while. Yuck!

I know the full well what the road treatments are doing to vehicles. Some of the brake lines on my 2003 Silverado have been replaced more than once and I just had to replace all of the fuel lines. But...Sounds messy and undesirable to me. There's gotta be a better solution?


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## ktfbgb (Jan 31, 2016)

Like was said above, just have it professionally undercoated. Washing down the underside of the vehicle after every storm goes a long way. I have seen guys that hook a garden hose up to a hot water source and hook up one of the oscillating lawn sprinklers like this one.
https://www.amazon.com/Metal-Oscill...ywords=oscillating+water+sprinklers+for+lawns
Put it under one half of the truck for a few minutes then move it over to do the other half. Or if you have one a steam or hot water pressure washer is even better but kinda sucks unless you have a lift for the truck.


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## Dogplow Dodge (Jan 23, 2012)

Google shultz gun.
Bought mine from Amazon. They offer a 4' plastic wand attachment, so you don't have to wear most of it.
https://www.google.com/search?q=sch...otafRAhVMxoMKHcUrATkQ_AUIBygB&biw=600&bih=960

Accuracy and less waste


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## hbrady (Oct 28, 2003)

I drove up on ramps, got under mine with a pressure washer, let it dry and applied LPS 3. LPS 3 dries to a wax like coating and it doesn't wash off like FF. Supposedly it lasts 2-3 years even with frequent undercarriage washes.


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## SnoFarmer (Oct 15, 2004)

LPS-3 works/lasts mulch better/longer than FF and you can get it in a spray can, gal can and pump-spray bottles too.


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## snowish10 (Oct 29, 2010)

SnoFarmer said:


> LPS-3 works/lasts mulch better/longer than FF and you can get it in a spray can, gal can and pump-spray bottles too.


 I wonder if we could use the spraye gun from the ff for lps-3. Where does everyone order lps from????


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## hbrady (Oct 28, 2003)

Best price I found was on eBay from Zoro. LPS 3 at room temp is about the same consistency as FF so the FF sprayer should work. I think I have said this before but it's important. LPS 3 creates a waxy like film which requires solvent to remove. Apply indoors or outdoors on a DEAD CALM day. Wear gloves, eye protection and at the very least a mask (full face respirator would be best). Also, I reached out to the manufacturer to talk about the flash point of the dried product because I knew I'd end up hitting exhaust components, here is what they said:

'try to minimize the overspray of LPS 3 however if it gets on the exhaust components, the product will melt away with minimum left to catch fire. I have not ever heard of this happening in my experience.'


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## scottL (Dec 7, 2002)

Here's what I do and it keeps for years when done right.

Clean/wash under side.
Brush/scrape all rust.
Spray with Dupli-color Rust fix. It will take two or three treatments. While it's curing temp and moisture are key.
Best undercoating I have found to date is; Rust-Oleum professional.

Long ago in Europe truckers would spray undercarriage with oil then drive on a dusty road. Today's oils will not work the same and many spray oils have all kinds of additives that will actually increase rust in some cases others will just not last but days or weeks.


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## RS69 (Jan 6, 2013)

TMLGC said:


> I do it in the late summer or early fall. Spray around underneath with a hose, let it dry a day or 2. I use used diesel oil with a spray bottle and brush. I do let it sit overnight. I use a can or 2 of FF as well in the doors under hood ect.


This what I have been doing and years and seems to work. I also apply the oil/gear oil mix inside the cab corners and lower door areas. I have also sprayed the mixture in a rust proofing spray gun instead of using the brush.


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## gtmustang00 (Feb 23, 2010)

I use bar and chain oil. So far, my 2006 f350 is still rust free...


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