The absolute best result I have had is a very fine wire brush (brass), alfoil and Penetrene
It got the the point where I was comfortable to remove the rust from the chrome petrol tank surround on my 1972 Sunbeam lawnkeeper (thats how confident I was it wouldn't stuff up)
Penetrene is expensive (cost $20 for a tin) but I have been using it at least 6 months and have only gone through 1/4 can - need stuff all and it just helps undo stubborn bolts so much.
For bulk work, I bought 2 (for $7 each on extra special) of these and expect to get at least 5 years out of them, then use the good metal cans. Still a steal at $10
With chrome mower handles, coke is fine (well, coles homebrand 'cola' I bought out of date for 25c a bottle). I think my habit of finding specials (and never throwing things away) stems from having close relatives who grew up in the great depression.
