Hi GB, I've got one of the universal clamp types. It works ok. (Edit: cost me £6.20 inc postage). Cable ferrule clamped in big end, wire out the small end, tighten firmly to clamp up tight and using the plastic tube from an aerosol can squirt oil into the hole. I use a 3 in 1 aerosol. The idea is that oil can't go anywhere but inside the outer cable (the other hole is to allow air out) but if you squirt too much oil too fast it comes out of that hole also. It doesn't take much to start coming out the bottom of the cable, so
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I looked into buying one of those blue 'Motion Pro' oilers, as it looks to be a good tool, but when I was looking it was only available to buy from the USA and then the postage makes it very, very expensive.