Read the manual. It probably notes that use of #2 is permissible, but not recommended. Sooting in the combustion chamber will be worse resulting in more burner service needed. A less drastic approach would be to have the tank refilled each time it is about half empty. At each filling alternate between K-1 and #2. That will result in a mixture. It will also confuse the heck out of your oil supplier.

Yes. Get someone that knows how to do it. #2 heating oil is
just this side of diesle. Winter diesle. #1 heating oil and kerosene are almost the same. What is your definition of expensive ? WARNIG. don't anyone tell me #1-2-3 heating oils are the same. They are NOT. I'll stop the argument right now. #1 heating oil has a carbon chain of 6-10
#2 oil has a carbon chain of 9-15. #3 is 12- 17, i think, don't remember. So if all heating oil is the same why are the numbers different ? Kerosene is lower than 6 but don't remember, been too long. Bottom line is the B.T.U. is different between the oils. You could go from kerosene to
# 2 oil and notice a difference. Kerosene to #1 and not notice the difference. What is the difference in the cost
between the to ? ( #2 heating oil is purple diesle ) Number one heating oil is the color of beer.

The burners on Miller furnaces are designed for #2 oil. In cold climates kerosene won't gel like #2 oil so thats why its used instead. Your burner doesn't care as much as your wallet does. I would suggest that once you start burning oil again have the burner set up by an efficiency test. The ideal solution would be to run a combination of the two fuels but highly unlikely that you will find a company willing to deliver from 2 seperate trucks to your house. Unless of course you want to pay dearly for that service. And that defeats the purpose for the switch anyway.

In my area, all fuel oil that is not taxed for use on-road is dyed red. No more amber-colored fuel oil except with the additional $0.50+ per gallon road tax added.