I have a stock, 2005 Ranger FX4 Off-Road. It has some rusting but none has "gone through" yet.

Does anyone have knowledge / experience with what's called hot oil undercoating?

I believe some kind of oil is mixed with some kind of paraffin so it sticks.

Small access holes are drilled into the door sills for application then plugged. I have no idea if this is good to do or an old fashioned holdover.

I'm looking for feedback. TIA

 

A few thoughts from the great white north on what I call dripless oil spray. I have a lot of vehicles sitting in my barn right now from the 70's and 80's and they were treated with dripless. They look great but are falling apart underneath. The waxy additive they use holds the water in! It clogs the factory drain holes and doesn't "travel" like regular oil spray. The cross ties under the box of my '80 (not ford truck @ 30 yrs old with 60K miles) were falling out onto my driveway but there wasn't a speck of rust visible from topside! They were really only wax channels lined with rust! Great stuff for flat surfaces but bad for boxed in components and frames. The other problem and it applies to all undercoating is getting someone who takes the time to do it right. A lot of places just push vehicles through and don't take the time to get it where it's most needed. I do my own and use a combination of summer weight chainsaw bar oil and SAE 30 non detergent oil. I do it every year underneath and every 3 years in the doors etc. This also has to be heated to apply because the bar oil is super sticky but doesn't build up. Hope this helps. Just remember that opinions are like butt holes, everybody's got one!

 

Never heard of it but I use woolwax, fluid film is another similar product.. You can get an undercoating gun and a gallon of the stuff and spray it yourself. I use the rattle cans for interior door panels. Recently repaired my cab corners and sprayed the underside and after a few drives in the rain the stuff is still there and not a speck of rust underneath it.

 

Take a simpler approach for my vehicles: keep 2~3 rattle cans of Rustoleum Black HiTemp & WhiteSiliconLube handy,
when under vehicles for any reason, wire brush clean any rust I see, then a fresh coat of black over that.
Once a year, spray lube into the interior bottoms of all doors+tailgates+fenders, plus the locks+hinges+hardware+bushings.
The State\County\City snow plows here do use MagChloride salt solutions, though sparingly, so bottom side rust\rot is less of an issue.
They use sand\gravel more than anything in icy weather, so sanded\chipped\cracked windshield replacement is needed every 2~3 years,
& keep color matched touchup paint for exteriors.