As a last ditch thing you could also try WD 40.
Try it on the chain first!
Give it a really good scrub up using a nail or tooth brush, (
or a pucka chain cleaning brush), you might just have a few links that are not fully straightening up and causing tight spots.
When all is nice and clean again, rub it down with an old towel or clean rag, which will clear up the excess WD40 along with the rust residue.
Then oil it with some thinnish chain oil like the new Castrol Racing Chain Oil, (
Halfords sell it, don't go for the other Castrol thick stuff), the new stuff is light and clean and following the WD40 it may free any links that had got a bit clagged up with surface rust and winter crap.
Check the chain again for tight spots and movement on the sprocket in the normal way.
Never got around to fitting a Scottoiler and I ride all year round, so this has been my standard chain treatment after every winter.
You may just find it feels a lot better, and costs little, (and the wife wont mind).
If still the same, the new chain comes before the wife, if you want to keep ridng!
