Get yourself a hand pump for quart size bottles. It should hold one quart, and yes, even a few ounces can set off the low pressure switch. I change mine once a year, along with the air filter, and I estimate mine burns (Or leaks) about 3-4 ounces. Purrs like a loud kitten. This pump is about $10 The only bad thing is it connects to the smaller hole opening of an oil bottle, and most have a larger pour opening. I just saved and reuse the same bottle.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1