Dinitrol 447 Underseal & ML3125 Cavity Wax Review [BMW E30 Underbody Restoration + Protection] 020

Dinitrol 447 Underseal & ML3125 Cavity Wax Application Review [BMW E30 Underbody Restoration + Protection] 020

In this BMW E30 restoration episode, I finally get the rear end of the E30 undersealed and protected from rust and corrosion. Further to that, I also apply a healthy dose of Dinitrol cavity wax to all the deeper, harder to reach areas and water traps in the chassis from the underneath.

Here's what I used in this video:
Dinitrol 447 Grey Underseal x4: https://ebay.us/FNUGrh
Dinitrol ML3125 Cavity Wax Brown x2: https://ebay.us/ImMTRD
Schutz Gun with Cavity Nozzle: https://ebay.us/LWUZej
150L Compressor: https://ebay.us/xxiVq8
Ranal Brushable Seam Sealer 1kg: https://ebay.us/Cget4u

After doing some research and getting some good recommendations on what to use, I decided to steer away from the standard Upol Gravitex, or Raptor Bed Liner and steer toward the Dinitrol range.

Seems the best stuff to use is Dinitrol 447 underbody seal, and to avoid the underside of my E30 looking like it had a load of Waxoyl brushed over the rust, I opted for grey instead of the standard black colour.

Dinitrol 447 reviews point to it being professional-grade, and the bottle corroborates that by saying it's for professional use only, but I manage to DIY it to a good standard.

Now I've experienced applying Dinitrol 447, it seems excellent, but there are a few pitfalls to be mindful of when using a Schutz gun and a compressor to apply it in a garage.

1. Firstly, even with the compressor dialled down to the low range of what is recommended (4-6 bar) on the bottle, it comes out thick and fast. So if you don't have your wits about you, you can very quickly create an unwanted run where it's gone on too thick. Keep the gun a bit further back and move it quickly to avoid this.

2. Secondly, and this is probably the top tip, the Schutz gun will gum up extremely quickly with Dinitrol 447, especially if you are trying to get the dregs out of each bottle and change them over too slowly. So when a bottle is empty, switch it out rapidly and don't dawdle. If your gun does get blocked, then thinners will break it down and clean it out. But it's extremely stubborn so it takes some serious effort to clean it out properly and continue.

3. Finally, get an extra can of Dinitrol 447. I got 3 cans to do the rear underside of the BMW E30, and I think that was the perfect amount if I hadn't wasted some trying to get the Schutz gun dialled in. Knowing what I know now, I'd have got an extra can. When I do the centre and front underside of the car, I will be sure to get a can more than I expect to use.

With the Dinitrol 447 having had a week to dry, it develops a kind of hard shell to it. Now I understand why it's over paintable. It seems like excellent stuff and looks great too.

With it dry, it was time to apply the Dinitrol ML3125 cavity wax brown to finish the anti-corrosion job off. This stuff comes in the same kind of tin and connects to the same type of Schutz gun to be applied, although you swap the standard nozzle out for a cavity one which is a pipe with a brass splitter on the end to provide 360-degree spray pattern inside cavities.

At first, I was a bit alarmed by the fact the Dinitrol cavity wax was so thin, and with the brown colour I'd chosen it looked like vinegar, luckily it doesn't smell like it, quite a pleasant wax smell actually.

The cavity wax is literally as thin as water, but as it dries it thickens up and leaves a waxy film coating on everything it gets on, one that repels water and is anti-rust too. Absolutely ideal for coating the inside of cavities in the chassis and behind body panels etc.

The application of this with the special nozzle is a bit less messy, but bear in mind it will run back out of the holes you apply it through and drip on the floor.

All in all, I'm very happy with the result and these professional-grade products can be applied in a home garage, DIY style. We're one step closer to putting this BMW E30 back together.

For more helpful how-to guides and restoration project logs, visit our blog: https://www.spannerrash.com/

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