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Is the new diesel interchangable?

Hey all. I’m a heavy equipment mechanic for 19 years so far, but I first started out going to tech school for air-conditioning and heating.

I had no luck getting a job in the latter field, but since I grew up in garages, I found myself working on Caterpillars.

Here’s the thing that I conflict with. I’ve done side work years ago on old oil burners for houses and I’ve run into many problems where the owner or tenant just put diesel fuel in the house’s tank if the price was lower then home heating oil. Let’s just say that what came out of that chimney looked like the house had a mile of coal cars trailing it.

Cleaning and putting home fuel in the system made us realize that home heating oil and diesel are not interchangeable. But now we have a new diesel which raises a question for me.

Are the two interchangeable now? I know if a person gets one’s tank dipped and if it comes up red then expect a problem relating to taxes if it’s in a highway vehicle, but say one has a diesel generator, or any off highway vehicle, or just a 98,000 BTU oil furnace. Are diesel and home oil now interchangeable? Can someone put diesel in their boiler and heating oil in their 420D? The thing is that half of the people I talked to say that both are Interchangeable and the other half say just don’t do it just to be safe.

All I was told by management was that if the customer admits to it then it voids the warranty.

P.S. You’ve been on the web a long time, and I have a feeling that this topic may have come up before, but sometimes archives get huge and humans get flustered, so I’m sorry in advance if this was brought up before.

To recap, what I mean by “you’ve” in the P.S. I mean “Car Talk” as a program in general.

I have a diesel car; have had one for many years. I would not feel confident that furnace fuel and on and off road diesel fuel are interchangeable. They were before ULSD according to a Benz owner who I knew about 20 years ago. The process to make ULSD (Ultra Low Sulfur Diesel) also removes the natural lubricity in diesel fuel and it needs to be replaced to lubricate the injection pump and the injectors. This is not needed for furnace fuel so it seems logical that the expense of adding a lubricant would be avoided for furnace fuel.

Off road diesel must have the lubricant, of course, is dyed red. If furnace fuel is also dyed red, is it the same fuel? According to the Internet, furnace fuel is also ULSD now.

Can furnace fuel always be No.2? Vehicle fuel must have No. 1 mixed in during winter to ward off cold weather waxing that can plug a fuel filter.

It could be possible that in some parts of the country that furnace fuel and off road fuel are the same to simplify the storage logistics but where No.2 fuel is heavily used for heating, there could be a difference.

Perhaps a tanker truck driver in your area would know more from being where the fuel is loaded. I talked to one who was filling a storage tank at a gas/diesel station about 20 years ago. He said that furnace fuel and motor vehicle fuel were the same thing but that was then.

Lots of unknowns here; possible others can say more.

we are probably running 60% diesel in ground fuel tank. I didnt feel like buying 100 gals when Mom’s house is heat pumped and she is 96yo and we have to pull out the tank. I’ve been adding 15gals to the tank when I think we are getting low. The fuel oil 3 years old. I am adding diesel conditioner on each 15gal fill.

It seems that from the little research I have done, the answer is yes and no. Home heating oil being more variable by region may present problems in some areas with motors using it as fuel. In cold climates, home heating oil has been used as a successful arctic blend in motors as after all, there are many in the north who store their fuel oil outside. IMO, it is correct for diesel manufacturers to discourage fuel oil being used in their motors. But, in one time use, if you must get from point a to point b, and there is nothing else…you use it. I know that to be the official position of my dealer for my diesel powered tractor. Occasional short term use may not result in long term problems…but there is may a significant difference in blends to make it discouraged.

Taxes and the ULS requirement guarantees Highway Diesel fuel will cost more than #2 Home Heating Oil…On the East Coast, I suspect Marine Diesel, Off-Road Diesel and Heating Oil are all the same product and any difference in price will be tiny…

The emissions systems used on todays motor vehicles will not tolerate anything but the Ultra-Low Sulfur stuff…