How prone are Porsche to rust?

[rdjohn]

I think Porsche generally were at the forefront of corrosion protection processes.

Early 911s had extensive corrosion problems arround rear wheel arches / C pillar, but from about 1976, Porsche were at the forefront of making steel bodied cars as well protected as reasonably possible. First came Galvanised coatings to all the steel used in the bodywork.

I had a '79 924 and it was amazing to see the difference to see what happened after stones chipped paintwork, compared to other contemporary cars, Capris etc. This was quickly followed by cavity sealing processes, wheel arch liners and all the stuff that today virtually every car sold in Europe is protected against.

As other have said, poorly repaired accident damage and neglect is your biggest worry. I think that German cars in general maintain their value because of Porsche's pioneering work in the 1970's.

[Rob996]

I understand that the rear crossmember of the 997 is prone to rusting through. Something to do with exhaust heat burning through paint and allowing all the joys of the British climate to do its best. Was documented in one of the porsche mags.

[battered]

Not Porsche but all cars post 1960s. Bodywork has improved, and so has engine sealing. As a result there is less oil leakage under the bonnet and fasteners and other parts do corrode. Couple this with improved reliability so things no longer have to come apart every few years and you will get more problems than you'd imagine. My own MX5 came with a worn out alternator belt, so I replaced it. The pivot bolt was seized, after much penetrating oil and some swearing, the bolt sheared. This is an M10 bolt, it's corroded in place where the steel bolt meets the ally, and it actually sheared.

WRT modern Porsches, I'd start injecting Waxoyl into the cavities and having an annual underbody spray with more of the same. It slows down the inevitable, and it's cheap.

[996TT02]

Yes 996 rust in the UK, definitely. Mine has lightly crusty sill edges, but even more surprising when the gearbox was out - quite serious rust patches in areas of the transmission tunnel which would be well protected from any crud etc. And lots of other places, the most irritating and hard to fix being the body-studs that pipe clips and underbody cover retaining nuts screw to. The thread simply melts away. In places I had to use screw clips (? - and star grips) pressed onto the remains of the stud, with the pipes retained not by the no longer usable screw on factory fitting but by a generic pipe P-clip. And although removable and replaceable (certainly not for nowt) the chassis struts / braces under the engine bay can corrode to flakes. In a few years time some 996 owners who overlook the issues will have some serious resto projects on their hands. As far as I am concerned they were not protected any better than any contemporary VW Polo or anything similar.