Just let natural oil leaks take care of things.

It will cost more than the cars worth and it will not do a blind bit of good.

Edited by Collos25 on 16/12/2012 at 11:09

Alernatively, seeing as the OP asked about undersealing not if those who can't be bothered think its a waste of time.

For the rest of the winter keep salt hosed off the underside weekly, best time is after a wet run.

Then when the last of the salt is gone give it a final thorught underbody washing and let it dry fully, then inspect and paint any parts that need it as necessary, brake calipers hubs etc, won't necessarily make them last longer but painted in black Hammerite they look a lot better than rust through the wheel spokes.

Then either find someone who sprays Waxoyl or similar product or if you enjoy getting absolutely filthy DIY.

If you DIY be sure to heat the Waxoyl in a pail of hot water to thin it, it will spray much easier, and i suggest pouring the first batch over your head, you'll end up plastered in the stuff so getting covered first stops you worrying about it..:-)

As said, the car will stink for weeks.

Just be careful who you deal with--my father had a 1958 Chevrolet Apache that he took in for rustproofing, and the workers bungled the job so badly that it actually *accelerated* the rust process...when he finally got rid of the vehicle there was little left but rust.

The most important thing on a 75 is to keep the drains clear under the wipers or you will be buying a new ECU its the death of many 75´s as is not replacing the various O rings on the cooling system on the 1.8.They have a complicated fuel sender and fuel pump under the back seat one on one side and one on the other.Pre BMW cars can be spotted because they have black sills BMW cars have the sills in the same colour as the car.A really underated car and a pleasure to own I think BMW only took Rover because it needed it to buy Mini which was only what it really wanted a shame really.

Don't bother, 75's don't rust.

The BMW-era "Oxford" (Cowley) ones can rust. Botched accident damage aside, the pre-facelift Longbridge Phoenix-era cars don't - they are superbly built.

I've restored many cars in my time.

Re rustproofing (although its been a while):-

I always use a warm Waxoyl / new oil mix. If you just use Waxoyl it can sit on to of layered rust - if anything making things worse. The oil in the mix soaks into the rusty layers.

If you don't have the spray gear use a Waxoyl starter kit:- Warm up the Waxoyl in hot water. Pour out half of the Waxoyl onto a container for future use, top up with cheap new engine oil (never used oil). Modify pickup pipe with a notch cut out near the top. Replace pipe/spray attachment with a lengthy fuel pipe with a bolt in the end and two holes drilled further back through the pipe (creating 4 holes). Pump up and watch the oil/wayoyl mixture "splatter" out of the end.

On the underside - I always paint on clean new oil - leave 24hrs - paint over with waxoyl underseal (yes it does! - but it is really messy). If you just painted on underseal over a rusty seam it comes back with avengance.

I revisited a 1967 Moggy Minor I restored in 1988 this year. Much welding had to be done back then ( sill structures, floors, rear spring hanger chasssis, wheel arch mounts etc...) and I rust proofed as above. On gettihng it started again this year involving changing a fuel pipe got my hands filthy on waxoyl/oil goo that was still tacky. Body where repaired in 1988 was perfect - had started to go on some areas that looked perfect back then (boot lid if only I had rust proofed this !)

Waxoil is rubbish compared to Dinitrol - tests have proved it.

The fact that you have to alter it to make it work says it all.

Personally I would not waste any money on a Rover 75...just service it and run into the ground..