Removed the cubby holes from the rear panels so I could see the crevice where inner and outer rear wings join. I could see that although my waxoyl treater had been in there and done their best, the spray might not have penetrated right into the crevice, leaving a chance that rust could still get going in there. I made up a dispenser out of an old ketchup bottle and a straw, put some Kurust in - and as best I could - dribbled it generously along as much of the crevice as I could. The theory was that being curve, and since there should be a wicking action into any rust, and along the seam, as the liquid falls down either side of the curve, then tehre's a good chance it will get to the bits that matter. I left it to do its thing for a day. I was pleased to notice Kurust dribbling from the rear of the outer wing, suggesting it had flowed back along the seam/crevice.
Next day I attempted to finish off the rustproofing by trying to use the spray on waxoyl that cost me £8 in Halfrauds. Useless as it isn't liquid (despite what it says on the can) and doesn't therefore hit the crevice line where inner and outer wings join, let alone run/wick along it. I resorted to something I've heard old timers swear by, and dripped lots of 5/30 engine oil along the crevice line so it could run down the line and saturate it too I hope. It'll be interesting to see if it works, and if the car smells of engine oil on hot days (hope not

Thought I'd share that with you....just in case. We'll have to wait and see how well it works. I have minimal rust at present, but one or two minor rashes appearing. The job itself though is v. easy. Just make sure you protect the upholstery etc. in case you dribble some where you shouldn't - its still quite awkward trying to get your dribbler into such a confined space and apply the dribble accurately (at this point I have to stop writing as I'm starting to double up with laughter)



PS - If you have a proper applicator/nozzle etc. you could probably get further in and apply the stuff more accurately.