Underbody wax - worth it or dealer BS?

[jimbo761]

Was offered one of these the time the car was in at the OPC. I have never had this done to any car I’ve owned despite running year round throughout the winter and haven’t had issues, but I usually run modern cars rather than classics which are presumably already treated from the factory. Car usually resides in a dehumidified garage and the underside looks pretty good to me with no visible corrosion at 7 years old despite 60k+ miles.

Any views, worth it as the car ages or unnecessary BS?

[Billy_Whizzzz]

There’s no such thing as ‘one of these’. It’s an expensive and specialist job to do it properly with dinitrol and you need to find someone who knows how to do it. It’s all the brackets, fasteners and clips that corrode first and while not structural can become a mess. Next thing is seams on sills etc. I’d definitely do it unless (like me) you don’t use it in wet or at all in winter.

[Turnpike1]

The Cayman has a hot-galvanized all-steel body. Add on rustproofing is generally a bad idea since it tends to trap moisture and dirt. And with a galvanized frame, it's pretty much pointless. Ymmv, other views no doubt available of course.

[WG]

I didn’t know that this sort of thing was still available - takes me back to the seventies on my back under neath ford capris applying it by hand ! I would say a waste of money on a Porsche with their fully galvanised bodies and all the under body plastic panels these days.

[Koln-RS]

Depends on the product.

There are water based products that can be applied to a relatively clean underside with temporary anti-corrosion and protective benefits.
Quite useful if the car is then going to be stored perhaps over winter.
But this would wash off quickly in normal use.

Dinitrol, and similar, are specialist products that require careful preparation, and provide long term protection to surfaces and cavities - most useful on older and classic cars.
Such treatments can take 2-3 days to correctly apply and cost four-figure sums.

[Turnpike1]

So, totally unnecessary unless you’re driving an old classic…

Let’s face it even an old 981 GTS will be galvanised so a complete waste of money…