"Lee Nowell" wrote in message
...
Thanks all great advice as usual. Bought 500g of caustic soda (£2 couldn't
believe it) added the whole lot to around 40l of cold water (instructions
said to use cold) and soaked them for a couple of hours. Water is now
black and most of the grease is off the rails. They now run back in fully
but not out fully so some progress. Cleanest they have looked in years.

Plan to get some more later and give them another soak to try and get the
final runner working a d remaining crud off.

You should be able to just soak them longer in the same
lot of dissolved caustic soda. You wont have consumed
much of the original 500g of caustic soda.