The type of fluid inside a compass is a simply a function of who manufactured it. All of the above answers are correct except for the whiskey! [It wouldn't work anyway as contrary to highland legends, whiskey is mostly water.] That urban legend came about in the 'good old days' from an excuse used to explain the bottle of Scotch kept in the calibration kit.
I once caught a Tamil labourer in our calibration workshop in Singapore mixing up a jug of alcohol and orange juice for a party. He was using our 100% Isopropyl alcohol
We do often hear of mass death incidents where poor workers have been drinking a bad brew - it seems like I nipped an incident in the bud there.
**********************************
Through difficulties to the cinema