Bought an old kerosene camping stove that was dirty and corroded. Probably never cleaned since the 30ies.
Earlier I have used citric acid but thought I should try something new. Mixed up a solution of hot water, oxalic acid, soap, methylated spirit and ammonia. If you intend to do the same, do it outside and wear protective clothing.
As with the citric acid it works best as log as the solution is hot.
After a short time the the stove looked like this.
And with some light polishing
Using a polishing wheel would have made it more glossy...