Deep cleaning...
 

...the chain: chain is fully intact and needs a deep clean and then to replace. I understand that soaking in pettrol will erode its internal rubbers. What is best to get the grime off and soaking in clean engine oil, for about ten minutes(?), to relube would work too? Thanks...

I use car/engine degreaser and a toothbrush..you can spray it on too. I re use an empty kitchen spray bottle.

I wash it down and dry with a air line before using a no fling spray ..WURTH is my fave.

Wd40 works miracles with a tooth brush. Then I use wurth dry chain lube

I bought one of those three sided brushes and some muc off chain cleaner. comes up like new.

Put on wife's washing up gloves.
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Cut up wife's best T-shirt in to a square.
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Hold wife's T-shirt in left hand and poor generously wife's baby oil onto T-shirt.
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Grab lower chain and roll wheel backwards through oil-sodden T-shirt.
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Repeat until nice 'n clean / oily.
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Put wife's T-shirt and gloves back.
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Deny all knowledge when questioned about above mentioned shredded Givenchy rag.
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Simples....:angel5: