Undersealing and rustproofing - r_welfare
Would be interested to know the thoughts of the assorted Backroomers regarding undersealing/rustproofing a modern car.

I know this was all the rage back in the 1970s with various companies such as Ziebart and Dinitrol being popular, and from seeing these "one previous owner - deceased" Escorts, Marinas and Allegros appearing on eBay looking pretty solid, the stuff obviously worked.

However I also concede that car manufacturers have, by and large, come a long way regarding rust prevention measures in the last 25 years.

Car in question is a 1999 Honda Accord with a paltry mileage which I intend to keep - circumstances permitting - for around 10 years. Are there companies out there that still offer this service, what are the costs involved, and would it be worthwhile?
Undersealing and rustproofing - PhilW
I must admit that years ago I used to always get under my car and give it a good "Waxoyling" in Autumn and Spring. However, as age has crept up on me and I less and less enjoy this aspect (especially since I tended to Waxoyl myself and it is very difficult to wash your hair afterwards!) I haven't bothered. My 1991 Citroen Bx was sold a couple of months ago with no sign of rust - and I think I Waxoyled it once years ago. My wife's Xantia (1993) was sold at 9 years old without a sign of rust and had never been Waxoyled. My daughters Clio is 10 years old - no sign of rust. My opinion is that rustproofing (with 6 and 12 year anti-perforation guarantees) by manufacturers has rendered aftermarket rustproofing unnecessary unless the car suffers some damage which affects it.And I think your Honda would probably last 10 years with no signs of rust with no extra treatment - in fact it would probably last 20!
But I may be wrong......!!!!
Undersealing and rustproofing - Altea Ego
well no doubt there will loads of people on here saying cover everything with x or y my thoughts are this:

Modern cars (and yours falls into this category) are very well protected. I would suggest that a once a year look see underneath with the car on ramps will be enough. Repair any sections that have had the factory underseal damaged, and that should be enough.
Undersealing and rustproofing - nick
I'd go along with RF's advice, a quick peek once a year and top up if necessary.
You may even do more harm than good spraying gloop around by blocking drainage holes etc.
On older stuff though, spray away every year.
Undersealing and rustproofing - No Do$h
The way Waxoyl lasts, somewhere out there must be a Waxoyl cocoon that used to contain a Lancia Beta Monte Carlo.....
Undersealing and rustproofing - r_welfare
Interesting points made - many thanks to all.

I still have some Waxoyl kicking around in my garage from when I treated my first car, a Volvo 340, way back in 1997 (Car Mechanics used to run a very useful series for 70s and 80s cars called "Stop The Rot" which used to show you where to inject the stuff), however for this one I was considering getting it done professionally.

Having said that seeing the number of 10 year old cars (mainly French I note - must be good design of the bodywork?) without rust, it does make me think doing nothing might be the best policy. I'm concerned that if there has been any attack of the factory anti-rust treatment (although the car has been in Guernsey all it's life, and has never seen road salt or an unmade road!), re-sealing a imperfect surface may do more harm than good. Will have a look around and if not, at least consider an annual steam cleaning of the underside.

I'm just mindful of my mother's last car - 1992 Metro, garaged from new and rarely driven in the wet (45k total), but still rusted out it's rear wheelarches three times in 10 years. Would hope that was bad design or poor metal/paint rather than anything else.
Undersealing and rustproofing - Rudolf
It's very difficult to find anybody doing traditional rustproofing now, and one wonders if there is any good in this?

Undersealing and rustproofing - Dizzy {P}
I first used Waxoyl in 1972 and have applied it to lots of cars over the years. However I don't believe there is any benefit in using it on modern cars as they are already very well protected.

I still have some Waxoyl but I use it only for coating the threads of components that I am re-assembling. It seals between the threads and makes the parts easy to undo next time.
Undersealing and rustproofing - Dizzy {P}
Sorry, it was 1975, not 1972, that I first used Waxoyl -- on the 1972 Triumph that I still own.

Despite several applications of Waxoyl, the Triumph still corroded between spot-welds and in some of the corners, places where it is almost impossible to get the stuff to penetrate. In fact I think it accelerated corrosion in these places as it prevented the joints from 'breathing' to dry out any dampness, which also happens with ordinary underseal.

When I totally rebuilt the Triumph in 1996-1998 I removed all the Waxoyl and didn't re-apply it. Instead I took great care to remove every trace of rust and then to get full paint coverage inside and out, and not a spot of corrosion has appeared since.
Undersealing and rustproofing - Mondaywoe
Interesting that someone has a 10 year old Clio with no rot. My Mum's 1994 Clio is unbelievably rusty underneath and I've just replaced both back wheelarches. It's only done about 43,000 miles and spends most of its time sitting in the garage - worst place for a car if you ask me! The MOT tester couldn't believe how bad it was this last year!I've resorted to coating it with sump oil now because cleaning it down enough to paint / underseal would be practically impossible.

Yet my previous car - Xantia - was also sold at 9 years - virtually without a spot of rust to be seen. Again, though, driven almost every single day in those 9 years!

Undersealing and rustproofing - M.M
I'm somewhat in agreement that modern cars are well rustproofed but not to the point of excluding extra treatment in some cases.

There are still good cars and bad cars for rust but by and large they are all miles better than anything from 25 years ago.

Possibly the greatest improvement has been the treatment of box sections and panel joins which gave rise to many problems in the past. Most cars are scrapped now with little rust, if any, in these areas.

However the actual underbody that is affected by rain, mud and any corrosive substances is still worth an extra treatment at perhaps 5yrs old, before any seam/surface rot sets in.

I use black Waxoyl on my cars after a gentle pressure wash. Always leave them a few days to dry after cleaning and do it in the warm summer period. I also paint it over all the suspension components that otherwise may look rusty.

Possibly it doesn't actually affect the life of the cars but it make me feel I'm doing my best for them.

Undersealing and rustproofing - 3500S
If my memory serves me right, Ziebarting as its known is a much more permanent process to Waxoyling. I've seen a few P6's sold with a line 'Ziebarted from new'. They do seem to have a smaller amounts of rust than non treated cars. I guess it must have been an option then.

Modern cars not only have galvanised panels but they are designed not to trap dirt and moisture, there's copious amounts of plastic used underneath cars to deflect water/salt from roads. Not forgetting to mention wax injection to protect welded seams. In older cars, they weren't designed not to rust unless they were aluminium which might explain why 85% of Land Rover are still on the road.

As for waxoyling, it's a necessary evil of owning an older car otherwise it literally rust in front of your eyes. You have to do it according to the weather, it has to be bone dry for a couple of days after a good hosing down and then applied on an equally dry, low humidity day otherwise you can do more harm than good. It's a messy job, the only thing similar I can think of is slapping on roofing felt tar for mess.

This summer has been great for dry weather, I got all the panels off mine, replaced rusty shims for polythene ones, checked for rust and treated all the panels and the bits of base unit I could worm a 1/4'' brush into. Even managed to check the monkey metal bumpers and treat the insides of them. Should get away with another 12 months without any welding work needed.

Happy to say that this stuff really does work.

As far as any other treatment, the only other stuff I've used is Hammerite on surface rusted '79 Fiesta rear axle, it was the only part of the car not to rust after that.
Undersealing and rustproofing - Garethj
As an additional note, older cars used primer which was slightly porous, therefore the metal could start to corrode from the inside depending on how it was treated before painting. Modern paints are much better, and I would say that most cars after 1990 are excellent for rust prevention.

As a few people have said, any rust is likely to come from damage from stone chips or an accident, so the best idea is to clean the car regularly and use that to keep a look out for any breaks in the car's finish. A gentle pressure wash under the wheelarches is a good idea, because if mud sits there it can trap moisture next to a place where there is likely to be a stone chip.

After knowing all this about modern cars, I sometimes have to be reminded why we like classic cars!

Undersealing and rustproofing - J Bonington Jagworth
"one wonders if there is any good in this?"

Despite the hype of the website, I think it probably does. What it describes is 'impressed cathodic protection' used for donkeys' years on oil piplines and similar. I saw a device like this advertised some years ago in the UK, but either people didn't believe it, or it got pulled for some reason. I suspect that manufacturers don't like it!
Illegitimi non carborundum!
Undersealing and rustproofing - J Bonington Jagworth
"oil piplines"

I knew what I meant...
Undersealing and rustproofing - borasport20
had a 71 Saab 96v4 and a 74 Mini Clubman, both of which had been subjected to one or other of these processes from new or near new, and all it did was to provide a thick layer of black gunk which concealed (and probably accelerated) corrosion of the sills and floor pan.

If someone were to try and sell me any car treated with the stuff these days, I wouldn't touch the car unless the seller stripped the treatment off or financed an independent engineers report. (Might sound OTT, but having bought the Saab then found nearly the whole of the floorpan falling out, 'tis the voice of experience)
Bora - what Bora ?
Undersealing and rustproofing - Robbie
With a modern car I shouldn't think it is necessary to rustproof as most have ten or twelve year warranties on rust penetration.

I purchased a new Vauxhall Omega 2.5 V6 in 1994 and the bodywork is immaculate, without a sign of rust. Indeed, the car has been totally reliable from new and has only had new tyres, exhaust system, front pads and cam belt and pulleys.
Undersealing and rustproofing - Andrew-T
I still have a 1987 sales brochure for the Peugeot 205 giving details of the 6-coat paint process which protected the body. There aren't many rusty 205s about - though many have an occasional spot, e.g.tailgate window surround - which suggests that DIY protection has been obsolescent for approaching 20 years.
Undersealing and rustproofing - Dave N
You can get it done at www.before-n-after.co.uk. They've been doing it for years and are highly recommended by the classic car mags.
Undersealing and rustproofing - Dizzy {P}
I remember Ziebarting well, including the fact that some well justified bad publicity led to the company pulling out of the business. The process was carried out by Ziebart franchisees, some of whom did a fair-to-middling job whilst others caused more trouble than if they had left the car alone.

There was a Ziebart franchise in Peterborough in the mid-70s and I asked them about supplying some compound for me to do the Triumph myself. I was told that only Ziebart's highly trained personnel using highly technical specialist equipment could do the job properly and he quoted some of the instructions from his manual to back up his claim. However some of what was said was clearly rubbish, so I decided to dig deeper.

When I asked how he would access the cavity between the inner and outer skins of the front wings on the Triumph, he said there was no way to get in there except by removing one of the hinge screws in the door pillar and feeding in a lance through the screw-hole. I informed him that almost full access can be gained by removing a headlight (three Philips screws) or going through some large holes in the inner wing that can be seen just by lifting the bonnet. He was clearly very surprised and admitted that his manual must be wrong.

I didn't get hold of any Ziebarting compound but I did set up a series of experiments with Waxoyl, both on and off the car. This was the *original* Waxoyl formulation and it performed reasonably well, however the modern formulation is too thixotropic to get between seams, even when diluted with 10% white spirit AND heated AND sprayed onto body panels which have been left to bake in the summer sun. Waxoyl thickens almost as soon as it hits the panel and simply covers over the joint seams. If you are lucky this helps keep salty water out of the seams, but it can also trap water in the seams and corners and actually accelerate corrosion.

Some of my experiments were carried out on squares of mild steel sheet which were given various treatments and then left on a sloping garage roof to face the weather. Obviously the squares left without any coating rusted quite quickly but what surprised me that squares where half was coated with Waxoyl and the other half left bare actually rusted more than the totally bare ones! It became apparent to me that water or condensation on the Waxoyled half was forming into globules which would then run down onto the bare half and keep it wetter for longer. This is one reason why I now hesitate to use Waxoyl unless I know that I can get full and penetrating cover, right down into the seams.

I found the best protection of all, on the experimental mild steel squares, was to let them rust very slightly so as to etch the surface and then to treat them with Jenolite followed by priming with BondaPrimer. Obviously this isn't convenient to do inside box sections etc. but I mention it just for the record.

Sorry about the lecture - but I do feel better for it. :-)
Undersealing and rustproofing - r_welfare
Dave N - I came across the Before-N-After site last night. Interesting to note they are only a couple of miles from my folks. However, prices for the "full" (I forget the specific acroynm used) treatment seemed very pricey (I saw a figure of £1,400 but that can't be right, can it?), and the basic treatment was Waxoyl-based, so I'm inclined to think DIY if I need to go that route.
Undersealing and rustproofing - nick
I don't touch waxoyl these days for the reasons given above. Dinitrol products seem to work much better and have come out top in tests in Practical Classics magazine. Dinitrol 3125 is good for rusty areas and penetrates really well. But I think once rust gets in, eventually it's out with the welder. These products slow things down, that's all.
Undersealing and rustproofing - Aprilia
I read a review in which Waxoyl came out very badly. Rather better was a product called 'Ankor Wax' from Morris Lubricants. I found it at a local motor factor for £13 for a 5l can. It is a bit more penetrative than waxoyl and is apparently what farmers use to spray their equipment with before laying it up.

I intend to get a couple of cans and give my cars a blast underneath with it - maybe next Spring.....
Undersealing and rustproofing - 3500S
Hmm, whilst not applicable to modern cars, this is very interesting stuff. No mention of a cautious use of hot air gun (or even a hair dryer) either to dry panels especially narrow seams but then I can remove mine ;)

There's still sections I can't treat, the worse is the rear valance just below the rear screen, a nightmare to dry and treat, I've had that replaced recently and I was assured that it was all treated before fitting the new one.

I'll look out for this Ankor Wax as Waxoyl is a s** to put on and I really need something that lends itself to faster and more accurate application.

And a nozzle can reach far more inaccessible places.

Value my car