Detroit Diesels and Fuel Additives

[DCMY #92]

I have 6V53s, have never had any injector problems, and never used any fuel additive other than Biobor JF. Although, since the boat has been undergoing a refit for the last 2 1/2 years I have not run any fuel through her.

I was talking with a very good local marine engine mechanic today who said that the diesel fuel in west central Florida is of very poor quality compared to that available in some other regions, and all diesel in the old days. He suggested that I should add Marvel Mystery Oil at a ratio of 1 gallon to 100 gallons to prevent injector problems.

Have any of you heard similar advice, or used MM Oil?

 

[ron6785]

DD's will run on just about anything. Try running the engines chances are you will have to change filters a number of times, but unless your injectors are spitting, Black smoke or evidence of fuel in exhaust water, then she probably just needs to run. Mine had been sitting for a year with very little running time because we had gone over 4500 miles on a trip prior to that. I fired her up for this trip and so far with a 1000 miles under the keel we havn't even had to change the first primary. Of course, we are not running at WOT either, so high performance is not the issue.

 

[REBrueckner]

Search the forums under "fuel additives" and you'll find a LOT of discussions:

Here is a recent one:
http://www.samsmarine.com/forums/showthread.php?t=12516&highlight=fuel+additives

and another..
http://www.samsmarine.com/forums/showthread.php?t=11470&highlight=fuel+additives

You'll find a lot of opinions and maybe some factual material as well, but one this is clear and that is that modern diesel dostillation methods results in a LESS stable fuel,,,meaning it's storage longevity is reduced. And its very likely lubricity is also reduced in modern fuel but whether the old Detroits need an enhancement seems largely a matter of opinion....


It also seems that fuel in southern climates is MORE prone to unwanted growth resulting in crud in fuel systems likely due to higher year round humidity and temperatures. A recent article I read suggested checking the first few gallons of each fuel fill via a fine strainer funnel and if it looks ok then filling at full throttle without the funnel so you are not sitting at the fuel dock all day. I think the article was by Steve D'Antonio and my experience is that he's pretty good on marine advice...