I have had many similiar scenarios discussed on here.....

I write it up first then call mx... I have grounded many airplanes and have had several cancelations due to mx. I have yet to get a phone call from my superiors questioning my actions.

Unfortunately we have some CA's here who continue to fly broke airplanes and don't write things up because they think they are being a "team player."
Little do they realize the reprocussions they are creating.

This is what you get when you have unexperienced 1yr FO's who don't even let alone do a good job as an FO whom have now upgraded to CA. They do now as a CA as they saw when they were FO's, and think this is the norm.

On to the original thread topic....

I hate to monday night quarter back, but.... If you see a history of abnormal oil servicing in the logbook then you should do a little more investigation before accepting the aircraft. Don't know about the B1900, but the Saab does have a maximum of 1qt/ 10 flight hours consumption. Your decision to accept that aircraft for a revenue flight has nothing to do with a union, and has everything to do with your experience as a CA. Now if you refused that a/c and you were told to fly it then that would be where a union would be able to assist you.

And about the rest of your day after your declared emergency... there's always that 7 letter "F" word that will take care of all your problems.