Protecting the Underneath

[malexander1050]

I bought a truck from California. 1987 R20 Silverado. The underneath is very clean and original but I have concerns. I live in Pennsylvania and within one winter season it will be eaten by rust. What would be recommend to protect the underneath aside from tearing everything apart..... My buddy said to coat the underneath with used motor oil....Any suggestions would be appreciated...

[Firebirdjones]

I personally would just keep it off the salty roads

I feel your pain though, I used to live in Cinci, and that's one of the reasons we left. I always had to keep a beater in the stable so the other stuff would stay nice.

If you really have to use it in the nasty weather, there isn't much you can do but undercoat, and try to keep the bottom as clean as possible with frequent car wash visits, but eventually the cancer will still find you.

[ray_mcavoy]

Originally Posted by Firebirdjones

I personally would just keep it off the salty roads

I agree ... that's the only way I've found to keep a vehicle completely rust free.

Originally Posted by malexander1050

My buddy said to coat the underneath with used motor oil

Your buddy is on the right track. I spray a mixture of hydraulic fluid and gear oil on the underside of my vehicles that get driven in the winter. I use the hydraulic fluid instead of motor oil because it has more anti-corrosion additives and I add the gear oil to thicken up the mixture so it doesn't run & drip off as easy. The important thing is to spray everything as thoroughly as possible ... especially into all the little nooks and crannies. In addition to the underside, I also spray the inner sections of as much sheetmetal as possible (inside doors/fenders, inside cab corners, inside rocker panels, inside bedsides, inside tailgate, inside the bed floor cross sills, and so on).

Unlike most undercoatings or anti-rust paints, I find that the oil works it's way into all the little gaps, seams, and pinchwelds and does a really good job of keeping the salt out of those areas. However, it does have it's drawbacks. It eventually washes/rinses off and needs to be re-sprayed every so often. I usually do mine every fall. It's also quite messy and can make it hard to notice leaks (so checking oil/fluid levels a bit more often is a good idea).

[Firebirdjones]

Boy I'll bet that car just smells like a working oil factory My wife would kill me if I parked something like that in the garage, it would stink up the house and drip all over the garage floor.

Bet that's fun to find oil leaks too, holy cow!!! You'd never know where it was coming from

[ray_mcavoy]

Yeah, it smells & drips oil for about a week after spraying It's usually parked outside on gravel so there aren't any issues with oil stains on the driveway or garage floor.

As far as oil leaks on the winter vehicles go, I just consider them as extra rustproofing so long as it's not a major leak (hence the recommendation of checking the oil/fluids more often).

I've also heard of folks using a mixture of oil and melted parafin wax and spraying it on while the wax is still hot. I haven't tried that yet, but it sounds like a good idea. The wax will thicken after it cools so the resulting coating wouldn't be as messy/drippy as the oil alone.

There are also some rust proofing products on the market that are cleaner and probably more environmentally friendly than the oil mixture I've been using. I've seen a few shops around here advertising one called Fluidfilm or something like that. Looks like it would do a good job if given a thorough application.

[donut]

Ray, at some point I've done most of your tricks (along with dumping some bar and chain oil inside the doors ) Fluid film does work, and does last longer than used oil, but it's not as cheap. If I had stayed up north, I was going to order up a 5 gal pail of the stuff.

Ideally, park it and get something else for winter.

On my '73, the only part of the sheetmetal that wasn't rotted was where 30 yrs of leaking oil coated it. (between the frame rails, it still had factory paint!)

[Rogier]

I drive in the snow a lot and salt is a serious threat. As a cheap solution cars are sometimes coated using Tectyl. This is a good solution for a short period of time, it chips and loses it's functions.

There is one professional solution that is also used in sea container ships, called Dinitrol. This is a non curing paint that fills gaps if your undercarriage gets hit by a stone or something. I don't know if they call it Dinitrol in the USA as well. It's easy to put on, but you get very very dirty.