Protecting underside of car - good idea or not?

[roberte30]

Hi,

I'm considering getting the underside of my car protected with Dinatrol. I'm torn between it being a smart idea to protect the car and it being a bad idea as the car will be less original.

The underside of my car looks pretty good but there are some rusty bolts and the exhaust connector support is rusty. Appreciate I can replace those parts (and I will) but I lost an E30 325is to underbody rust so it's sonething I'm concerned about as I plan to keep the car for many years.

The firm I'm thinking of using is jrclassics (http://www.jrclassics.co.uk).

Welcome your thoughts on whether I should do it and any pros or cons. Would you be put off buying a car professionally treated in this way?

Robert

[Marv968]

I used to use underbody wax protection on the underside of my cars, though I've come to the conclusion in recent years that you're better off stripping back all the rust to bare metal and using a permanent paint solution, overcoated with stone chip protection, then a top coat.

You're just covering over underlying rust using underbody wax.

[nw942]

I went through this with my car last year.

If like me you only tend to use it between April-September then just keeping it clean and spraying some water displacer/anti-corrosion e.g. Ferrosol may be enough?

On a related and hopefully relevant note, you can buy cheap USB borescopes for your smartphone/tablet for about £20, which would be useful in keeping tabs on rust in cavities and other inaccessible areas.

HTH

[CraigMillwardCroft]

Just drive in torrential rain always cleans the underside :thumbs:

[roberte30]

Thanks for your replies. Some good advice, although as adequate as the Super Sports are in the wet, I might skip the torrential rain :)

Stripping back to bare metal seems a bit extreme and expensive but would no doubt give a great result.

I share the concern that adding any protection could hide underlying rust.

I try to keep the car off the road as much as possible in winter but would be ideal not to drive it at all as suggested.

Jrclassics are fully booked until October so if I do get them to do any work, it won't be for a while. Based on the advice from you guys, I'm reluctant to have all of the bottom of the car treated. The cavity wax protection they offer sounds like a smart idea though, so that's something I might pursue.

I'll start with replacing the rusty bits and take things from there. Also considering stainless exhaust clamps. These seem good value at £25:

http://www.ebay.co.uk/itm/BMW-E46-M3-Z3M-Z4M-Exhaust-Flange-Repair-Kit-4-Flanges-stainless-steel-/381512112257?hash=item58d3e4d881:g:XxIAAOSwHxVW69F 2

And a more expensive option at £60:

http://www.ebay.co.uk/itm/stainless-steel-exhaust-flange-repair-kit-BMW-M3-E36-M3-E46-Z3-M-Z4-M-E85-E86-/172121487717?hash=item28133d7965:g:4jwAAOSwZ8ZW2JD Y

Would welcome any thoughts on whether either of these are a good option or whether there are any better solutions?

[0836whimper]

This stainless clamps for £25 seem very good, as long as they work. For many years no-one was making anything to replace the terrible BMW ones, driving owners slowly nuts...

Don't forget you'll need the gasket/seals also, cheap and ordered from BMW.

[J77]

A car with a treated underside wouldn't put me off. It would be one less thing for me to think about.

[roberte30]

Thanks for the tip on the gasket/seals. Will get them replaced too.

It will be a few weeks before I get the clamps fitted but when I do, I'll report back on them so others know if they're any good.