I'm told Propane is selling for approximately 0.50 cents a Liter less than Oil here in Eastern Ontario presently.. We've gone over the Burn Cleaner & Effecientcy Factor... My Query is Comparing what we put out in cost of Oil Heat last Winter into Propane Expense, if that is a fair question? We began with a 1/4 Tank and had the Tank topped up twice last Winter , we now have 1/2 a Tank to start this Winter.. Each time they top up the Tank, the gauge is diseaving as it reads 3/4's full when he pulls the nozzle out... Having said all that despite the lingering cold temps into Spring this Winter our average is about the same give or take dropping 857 liters of Oil Fuel in the Tank this Winter... If anyone follows what I'm getting at , Please & Thanks

I'd calculate what the cost per BTU of each is for you. THen factor in the efficiency of the heating system of each. That should give you a good guess which will cost you less.

Unfortunately you are making a major outlay to buy either if you don't have them now... and the price of either fuel can rise or drop significantly based on demand which isn't always linked equally to the price of crude, though both are products of it.

Presuming the same efficiency between appliances, you will burn 1.5 liters of propane for each liter of oil. Less routine maintenance costs with propane, usually.

All that matters is how many liters you used over a heating season.
If it was 875, then buying propane would save you .50 x 875, or $437.
(If you had 1/4 tank and ended with 1/2, then you used 1/4 tank less than 875. You don't say how many liters your tank holds, so you have to figure that out. And multiply that by .50 and subtract.)

joypulv's answer presumes you would use the same amount of propane as you would oil. With oil having 1.5 times the BTU content per volume, it is highly unlikely you would burn the same volume of propane as you did oil. If the furnaces were the same efficiency, you would burn 1.5 times as much propane.

OH! Thanks Grady White!