Oct 19, 2012
I would like to know if it is a good idea to oil spray the undercarriage of my car. I have had differing opinions on the matter. Regardless my car is a driver and I would like to protect the frame etc. Any thoughts ?
My only concern is with dirt and stuff sticking to the oil which would trap water. I wonder what company's use when they do their anti-rust treatment. What are you planning on using? I always thought of buying zinc blocks and bolting those to my frame.
My '75 has been sprayed with Krown before by the previous owner. I haven't done it since. I have both of my regular vehicles sprayed with Krown every fall. The city here sprays all of its plows with Krown every year to protect them from the salt. The nice thing about Krown is it isn't heavy like a used oil spray. If you don't care about having a show car underneath then go for it.
I believe in krown my first car was an 88 Honda prelude some rust around the windshield and fenders started the krown profing every year and rust didn't spread anywhere had the car for 5 years when I got rid of it there was no new rust on the car
One thing I did was to jack the front end up much higher than the front ,plugged any openings and attempted to fill the frame with used engine oil .That was back in the mid 80's and I remember it wasn't a great idea .:D

I do have an extensive list of things not to do and it's in order of Dumb ,pretty dumb,really dumb and don't tell anyone ya did this ever.
Last edited:
I used to spray the under side of my vehicles with used motor oil. What I found wast that after a while there built up a layer of dirt. Scrape it off with a scraper and there was still rusting going on behind the layer. It appeared that all the oil got absorbed into the dirt with none left to protect the steel. Fluid Film seems to be a good coating that creeps but doesn't drip. It seems to do the job. I think any of the name coatings today probably do what they are supposed to do. When I restore the '72 Lemans Sport a few years ago, It still had the Ziebart sticker from the early '70s when the car was new. The stuff was dried out, cracked and brittle like a poor quality paint. It protected nothing and the car was rusted in all the usual places. The name is still around but I certainly hope they changed their formula as it was a total waste from what I saw after disassembling the car.
Our '97 Olds doesn't see winter and has never been undercoated. The car still looks pretty well like new top and bottom after 125K miles of summer driving. It is always garage kept too. I wouldn't worry too much about our Corvettes but a little under coating sprayed into the frame wouldn't hurt.
I have read about por 15 (paint over rust). Would this be a better alternative? Just por the entire undercarriage. The car is never winter driven and garage stored.

With respect to the oil spray the nay sayers have all told me that the dirt from the street will stick to the bottom and the car will look terrible. I thought the oil would some how keep it shiney....I guess not!
I've used POR15 on parts. You can brush it on and it flows out so that no brush marks remain. Just don't get it on your skin. Lacquer thinner will take it off if you get at it right away. Otherwise you will be wearing it until it wears off. You would want to wire brush or wire wheel loose and flaky rust before painting. It won't do everything for you but does look good when done.
I too believe in oiling my winter cars especially inside the frame where the brake and gas lines run to help to extend their life BUT be careful not to get oil on any bare fiberglass as it will wick through the glass and lift any paint that is on the other side over time. Once you get oil into f/g it is next to impossible to get out. People have discovered this when an air-cond compressor sprays oil on to the inside of the hood, next thing they know is the paint on the hood is blistering up. There are quite a few threads on this on the US forum ... just sayin' ... Rob
krown is a good choice on a yearly basis for daily drivers that see winter use. i have used it on different vehicles with success. however, our corvettes rarely see bad weather let alone winter so keeping the underbody clean is our main concern. this would be tough to do with an oil spray product. as a personal preference i would go with por 15. keep in mind too that the cars can still be exposed to corrosives in the summer. many areas use calcium chloride as dust control on unpaved rural roads.
I had a 94 Sonoma that was Krowned yearly since new and the underbody accumulated an approx 3/8" thick layer of Krown soaked dirt over the course of 15 years. Although the vehicle remained virtually rust free, it must have added some weight and anyone working on the truck quickly became covered in the residue soaked 'tar-like' substance. Krown continually crept around body seams making the outerbody attract dirt resulting in an increased need for washing the exterior.
I still use it on my daily drivers but would not on the vette.
Old Thread: Hello . There have been no replies in this thread for 100 days.
Content in this thread may no longer be relevant.
Perhaps it would be better to start a new thread instead.

Similar threads

Users who are viewing this thread