Should I change my oil after I have found the leak and repaired it?

hi, i wanna build a simple AM valve/tube radio. the grid leak detector has come to my attention. i am referring to the resistor and capacitor in the grid circuit: http://www.bolis.com/amillar/pg/rdamh/fig048.png what is the resistor for? as i understand it, the electrons floating by the grid sometimes hit it, naturally pushing it negative with respect to the cathode. how far negative does it go? to the cut-off point of the valve, or just to the point where the grid stops acting like a diode with the cathode?

I own a fleetwood travel trailer, 2006 and the LP GAS LEAK DETECTOR Pre Tell 26 by CCI Controls goes off at least 1-2 times per week. The detector I have is brown and horizontal, it has the Green Operating light which is always on when the RV is in use and the Red Alarm light which is the light that turns on, and also the green Fault light which has not yet turned on at all. In small letters under the Fault Light are the words (Low Voltage). The red alarm light turns on normally around 8 or 9AM but no propane smell. Why would their be if the tanks are empty and disconnected? The propane tanks are empty and the batterries are disconnected because I don't need to use them right now. I do have my RV plugged in only to use my TV and Refrigerator every once in a while (Nothing is wrong with my electrical source/connection).