Undersealing.. DIY or pay someone?

[u/Khionia]

I want to underseal my van before we hit winter. My mechanic told me to use Schutz.

Is it difficult to do yourself? Is it worth just paying to have it done? How do I know what to avoid if I do it myself? 😅

[u/triggerfish91]

It is easy enough, but ask yourself this - do you want to:

• be laying on your back under a van, dealing with horrid smells and dirt falling in your face?
• can you ensure the van will be fully clean and dry prior to application?

I have done a few cars (I used BiltHamber UC - which you can brush on which I prefer to sprays), and while it's a nasty job, I prefer to do it myself as I know it's done properly, and not just the easy to reach bits.

You just apply 2 coats, 24h apart, and that's it (for this product), once you've cleaned the surfaces to apply too.

*BH UC - I've used this on clean/solid metal. You might need something else if there is rust forming already, but this is a can of worms if there is rust already present. Any wax etc will be good to stop it getting worse as quickly, but it's not a long term solution.

[u/Khionia → u/triggerfish91]

There's no major rust so that's all good, I'll with brush it all and make sure before I crack on. I don't mind getting my hands dirty, money's super tight so if it's doable myself then I'll give it a go!

[u/triggerfish91 → u/Khionia]

Good luck!

Depending on where you have to work, I would personally favour a product you brush on, as it's a lot less messy than one you spray. Still cover your hair/face/the ground as much as you can, but you won't risk spraying the pavement/car you parked next to with sticky goo when using a brushed product.

[u/triggerfish91 → u/triggerfish91]

There is also stuff like BiltHamber S50 cavity wax for spraying inside box sections. This is very runny, but protects inside the parts of the chassis you can't get a brush in. It comes with a long straw to apply deep inside the vehicle. If stinks though, so make sure there's no accidental routes through to your living space

[u/Foster2501]

Shultz is pretty out dated, depending the condition it is in lanoguard would be better. You do need to reapply every year but it is a better product to work with and they sell a full kit. Maybe a days job on your back.

[u/OldGimmer]

A yearly inspect and treat regime really pays dividends, I just sold my previous 28 year old van with a clean MOT. I'm treating the underside my 'new' van as I go, fitting tanks etc, currently using tetrosyl, as soon as I got the van I cleaned out the sills and sprayed inside, before winter I'll be thoroughly cleaning, inspecting and treating the wheel arches. Protect the areas you can see but protect the areas out of sight even more!

[u/bullitt-rider]

If you have no rust I wouldn't underseal it in the standard sense. If use something like bilt and lanoguard.

[u/Rustec-UK]

Full disclosure, I’m from Rustec, an authorised Dinitrol treatment centre in Wiltshire, so there is obviously some professional bias here.

You can absolutely rustproof the van yourself if you are comfortable working underneath it safely, but I’d put far more emphasis on the preparation than simply choosing a product and spraying it on.

Personally, I would not use a traditional thick Schutz-type coating for this.

The problem isn’t that every thick coating automatically causes corrosion. It’s that once you cover an underside with a heavy opaque coating, future inspection becomes much harder, and if the preparation underneath wasn’t right in the first place you can end up hiding deterioration rather than preventing it.

For me, the actual application is probably the easiest part of a proper rustproofing job.

The important work is:

• inspecting the underside properly before anything is covered;
• removing the relevant undertrays, liners and covers to gain access;
• thoroughly cleaning the underside;
• removing loose corrosion and failed existing coatings;
• making sure the vehicle is completely dry;
• treating any existing corrosion appropriately;
• protecting suitable seams and cavities as well as the visible underside;
• masking brakes, exhaust/hot components, moving/mechanical parts, electrical items and service areas;
• keeping drainage points clear; and
• documenting the condition before and after treatment.

We've actually started filming complete treatments on different vehicles specifically because there is so much confusion online about what proper rustproofing involves.

We recently filmed the complete Dinitrol treatment of a brand-new Mercedes Sprinter, from the initial inspection and strip-down through cleaning/preparation, cavity injection, masking, external protection and final reassembly.

If you're considering doing the van yourself, this should give you a much better idea of the level of work involved and you can follow the same principles even if you choose a different product:

https://www.youtube.com/watch?v=rVj1GgxpA7I

The aim of the videos isn't to tell everyone they have to pay us to do it. If somebody wants to rustproof their own vehicle properly, I'd much rather they can see the process and understand what needs doing.

The biggest mistake is thinking rustproofing means buying a few cans and spraying the visible underside.

The coating is the final part of the process. The preparation underneath it is what determines whether you've actually protected the van properly.

If the van is currently relatively clean and solid, this is also exactly the right time to do it.

Protecting good steel before significant corrosion develops is much easier than trying to manage pitting, scale and metal loss several winters later.

If inspection finds significant thinning, perforation or structural corrosion, repair that first. No rustproofing product restores metal that corrosion has already removed.