-
-
-
-
-
-
-
-
-
-
-
-
-
Disassemble all, including shifters, and bath it in penetrating oil. Change inners AND outers, put it all back together, replace worn out drivetrain parts. If a derailleur is too far gone is worth replacing, even if you get it back moving it will rust again.
Worth getting serviced in a shop with a parts washer IMO -
-
-
-
-
-
-
-
-
-
-
150ml or cl? You need a good amount for that tire