Marine Diesel vs Automotive Diesel

Jan 12, 2019
Hunter 340 Narragansett
While sitting at the mooring today I watched someone with 2 - 5 gallons cans of diesel fuel pouring it into his fuel fill on his boat.
It's a Hunter 386 so I had to ask if it was diesel fuel. He said he was topping off his tank and always used automotive diesel and marine mix. He felt he gets better performance out of his engine.
Seems like a lot of work to me, but to each his own I guess.
Aside from the fuel color of each one, is there a difference or benefit to doing this? Can the performance be noticed? Cost difference isn't a real concern.
It will be interesting to get opinions on this.
Sep 25, 2008
Alden 50 Sarasota, Florida
Same thing, different color. Dyed to depict road tax applicability.

Guess his boat gets “better performance” with red dye:)
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Jan 12, 2019
Hunter 340 Narragansett
That's what I thought. Looked pretty heavy to me.
Maybe someday we'll be next to each other and we can race. Although this a 386 vs my 340, so I'll need handicap.

Ward H

Nov 7, 2011
Catalina 30 Mk II Barnegat, NJ
I have a friend who bought his diesel fuel at the gas station. He said it was cheaper and easier. I've never compared prices but it sounds like too much work to save a few dollars since I burn less than 20 gallons a year.
Jan 7, 2011
Oday 322 East Chicago, IN
I use 5-10 gallons of diesel a season. I usually dump a 5-gallon can into the tank when I am bellow 1/2 full. I use a siphon hose so not to spill any fuel.

I think using Jerry cans is frowned on in the Marina (both because the marina wants the fuel sale, and because of the potential for a spill).

Yes, as @Don S/V ILLusion said, non-highway fuel is dyed red…don’t get caught putting that in your F250.

Feb 21, 2013
Hunter 46 Point Richmond, CA
Ditto Don S/V ILLusion. Oil refineries manufacture one diesel product (Ultra Low Sulphur Diesel [ULSD] having no more than 15 ppm sulfur plus a host of other specifications) that is sold into the on-road diesel and off-road markets. I also periodically top off my Hunter 46 from 2.5 gallon containers since the marina the nearest marine diesel fuel station is over 5 miles away, it is fast and easy AND never seen a performance difference with on-road vs. off-rode diesel in my marine engines. Theorectically, off-road diesel should be cheaper than on-road diesel since it does not include excise taxes. The OP might share this article with the Hunte6 386 owner Difference between On-Road and Off-Road Diesel | McIntosh Energy .
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Apr 13, 2015
Catalina 309 Tampa
I've always used on-road diesel in my boat. I don't find it difficult to siphon a jerry can when needed. I find it cheaper (which it shouldn't be since it adds the taxes). The main reason I use it is that I believe it is fresher due to the number of diesel vehicles filling up at the station I go to....

Dave in Charlotte Harbor
Mar 6, 2008
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
I use 12vdc diesel fuel pump to transfer from 5 gallon jug to the tank. No spills. Gas station diesel is fresh since it is purchased and refilled more often than at the marina and it is noticeably less expensive. I keep the tank full to avoid moisture buildup in the tank.


Jan 22, 2008
Tartan 37 Pensacola Shipyard, FL
The best diesel can I ever bought was from a company that went out of business because they were sued by an idiot (or his wife) when he got burned pouring gasoline out of one of their jugs ONTO A LIT FIRE!!! Evidently, that warning was not on the side of the jug. Anyway, he got a jury of his peers and won. But the company and us lost.

You could lay this jug on its side with the hose down the fuel filler and then open the valve and let the diesel flow out. I never spilled a drop while fueling onboard. Can't find a suitable replacement these days.
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Jan 7, 2014
Beneteau 45F5 51551 Port Jefferson
This is the best siphon hose for fueling, never spill a drop and you just giggle it up and down to start the siphon.
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