Is Wax-based underseal a waste of time?

I think corrosion is basically down to the quality of the steel and not the corrosion protection. I spent my whole working life in the construction industry (now well re-tyred) and had much to do with steel and corrosion protection. We used steel sheet piles in marine environments often with minimal corrosion protection but the steel quality was "high". They are expected to have a working life of decades. We used Corten grade steel for fence posts in a motorway environment, bare steel which gets a surface rust and no more, it will last forever. 20 odd years ago I was in charge of a job shot blasting and painting the main rail bridge over the Thames into Victoria, a job which has to be done every 15 years, and never saw any rust on the structure, even inside the bare steel hollow members. Again, top quality steel originally used. Ever seen a rusty manhole lid in the road? again high quality ferrous material. But cars are made out of much lower grade steel, it only has to last a few years before the car ends up in the scrapyard. The steel used in automotive applications will corrode from the inside out no matter what corrosion protection it is given, it breaks down chemically. I don't understand the galvanising chemistry but do know that it will massively extend the life of lower grade steels. In a nutshell, car grade steel has a relatively short design life no matter what corrosion protection you give it. (Galvanising excepted).

When we had the farm every year we would coat the plough shares in a mixture of old oil and grease, kept em spanking for the next season.
You probably wouldn't want it under a new rangerover though

I spray my vintage tractors with a mixture of Oil and diesel, stops them rotting and makes 'em shiny like glass

On the RRC from post 89 they used 16 gauge that was contaminated from factory, if you were to scrape off "good paint" you could see the contamination in the steel, my 91 Vogue 's inner arch was rust free but under the paint the steel was covered in blotches and minor pitting!!

Everything in the 90's made by LR seems to have rotted out faster than any other..

Henry_b said:

Everything in the 90's made by LR seems to have rotted out faster than any other..

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Took them a while to catch up with BL then.....everything they made from the late 60's fell to bits and went to Alfasud heaven.

lightning said:

I’ve used various products all wax based and supposed to stay flexible.
The issue is, the rust seems to just carry on behind the coating.
The coating still looks fine, it hasn’t washed off or disappeared, but when you scrape it off, there’s flaking rust behind.
Those outriggers weren’t that rusty when l bought the 110 in 2004. They were mostly still paint.

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Painting wax on paint protects the paint not the steel. Original chassis paint being what it is releases from the steel and moisture creeps under it. It then protects the rust from the wax.

I actually like waxoil But I use it the same as I would use raw grease. It is a high maintenance finish but has the advantage of taking little time to warm, scrape off and renew. It kind of makes me keep checking and poking regularly and indeed has saved discovering rot that has ruined full sections.
Applying the latest all singing and dancing ‘permanent’ solution can stop you checking for rot as regularly as you should leading to complicated repairs. there isn’t a permanent solution and I doubt there ever will be otherwise the forth bridge painters would have been out of work many years ago.
I have had issues with a new rear section of chassis on my series as the jap black factory finish is next to useless and short of encasing it in a vat of resin like a paperweight, it was destined to slowly release from the steel allowing salty water in. Fortunately a regular scrape and touch up has kept things maintainable. Probably not an option with a two pack, £100 a tin dinosaur cack as even that only protects the factory paint never fully contacting the steel itself without a full body off grit blast.

Just replacing a ripped off rear mudguard - bit of scotchbrite (other products are available) to key the area and a blast with wax oil before I refit (the hanger not the mudguard). something I have done several times as the damn things keep falling orft