As long as it stays above freezing all citrus should survive. Putting a small fan in near the ceiling that blows air down (circulates the heat near the ceiling back down to where it does good) can help. Make sure the pots are on insulation and not directly on a concrete floor if it really is touch and go.

You can also wrap the trunks with newspaper to help. Leave it on all winter.

While wet soil retains heat better than drier soil do not overwater your citrus.

Warm water can burn the roots...remember trees and their beneficial soil organisms are not used to temperatures much above 30-35C. They can be killed off. You can fill pots/barrels/containers with hot water for overnight release of heat.
But as long as it doesn't fall below freezing....

Thank you. Your idea of fan to circulate the hot air is good. I will do just that.
Abe

I can vouch for the wrapping of the trunk - it really helps. I protect my outdoor Satsuma by wrapping the trunk before a cold snap. I have been setting my containerized plants on a couple of old cardboard boxes to keep them out of direct contact with my concrete.

I have a large hoophouse that I seal up and use like a greenhouse during the winter. Because it has only plastic sheeting for walls it doesn't hang on to any heat so it is hard to keep "tropical". One surprising thing I've tried is to build another smaller greenhouse inside the larger greenhouse, sort of a tent made out of this very thin clear plastic I had on hand. By placing the tiny electric space heater inside that tent I can keep those plants very warm. So I try to keep the large area just above freezing and never have to worry about the small area. You might be able to build such a temporary tent out of thin plastic (I just used ropes and clothespins to build mine) and put the heater inside it, instead of heating the entire garage.

We have our drier vented into our greenhouse. It has been below zero for weeks. At night we put a wet beach towel in the drier and the end result is a warm humid area that is above 50 much appreciated by our 13 citrus (2 avocado) trees that must live in the Utah Rocky Mountain high desert.