Diesel Fuel

[casey1999]

Is there any difference between diesel fuel you buy at a gas station/truck stop and "marine diesel"? If so where do you buy "marine diesel" and how is it different from auto/truck diesel.
Regards

[SecondWindNC]

Short answer is no - your engine won't know the difference.

Longer answer is that there are different taxes on diesel based on use - road vehicles vs. marine vs. farm/commercial, etc. Color additives are sometimes used to differentiate between these. But there's nothing to stop you from using diesel from a regular gas station in your boat.

[chuck53]

I'm pretty sure there's no difference except for price.

[PhilipStevens]

Originally Posted by casey1999

Is there any difference between diesel fuel you buy at a gas station/truck stop and "marine diesel"? If so where do you buy "marine diesel" and how is it different from auto/truck diesel.
Regards

Do you have Bio-diesel in the USA??

In the UK, road diesel (DERV) has around 4% or so, bio diesel additive. Marine (red dyed) diesel (at this time) does not.

Road diesel attracts full tax, but marine diesel has a lower taxation.

Farm vehicles and road maintenance vehicles can also use red diesel.

[remetau]

The road diesel is also ulta low sulfur. I add Mystery Oil to my diesel to add extra lubricity.

[MarkSF]

Originally Posted by casey1999

Is there any difference between diesel fuel you buy at a gas station/truck stop and "marine diesel"? If so where do you buy "marine diesel" and how is it different from auto/truck diesel.
Regards

Marine diesel has lower tax. This means that it would be illegal to run marine diesel in your car as you are dodging some tax.

But it is OK to run auto diesel in your boat. You are just wasting some money on extra tax. However, the auto diesel often sells for less than the marine anyway.

For a short while auto diesel was ultra low sulphur, but marine wasn't. I believe that now they are both the same stuff, ultra low sulphur.

[casey1999]

Originally Posted by MarkSF

For a short while auto diesel was ultra low sulphur, but marine wasn't. I believe that now they are both the same stuff, ultra low sulphur.

My 30 year old yanmar 3gmd calls for:
"As further insurance of satisfactory operation, use fuel having less than 0.5% sulphur."
so I assume ultra low sulphur fuel is good. Is this correct?

[MarkSF]

I did some research on the interweb and as usual was left very confused. However, you can only buy ultra low here in CA, so there doesn't seem to be much point worrying about it.

It seems that ultra low might have slightly lower lubricity and slightly higher combustion temps, but it probably doesn't matter.

[smurphny]

Here in NY there does not seem to be a large price difference between dockside and automotive price for diesel if you know where to get it....it's all overpriced. How is it that diesel, being less refined, costs more than gasoline which is much more refined, requiring more $ to produce?

[MarkSF]

I don't think low-sulphur diesel is less refined. There's an extra process to remove the sulphur. It's the same process that produces jet fuel.

Then it comes down to supply and demand. The prices of the two fuels are set mostly on a global basis, ignoring tax. Diesel is in a lot of demand worldwide, as more and more cars use it. So is jet fuel, and heating oil, and they all start with the same fraction.

Finally diesel is denser and contains more energy - so you're getting more fuel for your money, if you measure by weight or by energy.

By what measure is it overpriced? It's cheaper than bottled water. It's a limited resource. It's in great demand all around the world. You might want to pay less for it, that's not the same as it being overpriced.