Hey guys...got a question what should we use in our mercs to overcome ULSD and messing up seals or orings like I have heard it does...what additive? I have seen and used diesel fuel catalyst...but not sure..

I use the diesel fuel catylist, but for other reasons.

The reason it affects older o-rings is a combination of the lack of elasticity of the old rubber, and the reduced seal-swell from the lower aeromatic content of ULSD.

It seems in theory that adding a solvent to the diesel fuel that will increase the seal swell would prevent the problem, such additives are often used in the production of biofuels and WVO products and I'm guessing that seal leakage is less common for those running bio and WVO for that reason.

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Gone to the dark side

- Jeff

I use Marvel Mystery Oil with some Power Service Kleen Diesel, and my car seems to really like it. Both have lubricating qualities and PS boosts cetane, so it seems as though all my bases are covered.

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1975 240D (Euro 4spd man, Gold, 126,000km)

I have some Lucas fuel additive that I use ... often I buy grocery store 10-30 motor oil @$1.25/qt or less and add 5 oz per 10 gals or so of fuel.

I read many post of folks who don't believe extra lubricity is necessary, but I have strong memories of my parents trying to get home to NC from my sister's in Phila when the Feds did the first big change to diesel fuel, and having the engine run a couple of hours before the IP locked up. There were tractor-trailers all over the place, too. They finished the trip on the cab of a flatbed tow-truvk, with the car on the back. They started adding ATF with every tank & had no more troubles ..... and the IP survived and is still running, as far as I know, with no signs of distress. So I add a lubricity additive.

Many of the Dodge Ram Cummins turbodiesel forums that I visit recommend 2-stroke oil.

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2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
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'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

Replace the seals as they leak, nothing you can do about it. Age plus a new additive package is causing a bunch of fuel leaks.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

People are probably spending more money on snake oil than it will cost to replace seals if/when they eventually fail.

I also have a '02 Ford Powerstroke & I have found that the use of 2-cycly oil mixed 1 oz. to the gallon works wonders for my engine. It quieted it down considerably, runs better & I even picked up a mile or two a gallon mpg-wise.

Keep in mind that the additives such as PS Diesel Kleen, etc., are full of things like acetone & other solvents. Might be OK for an occasional treatment, but nothing you'll want to run in your engine forever.

See: http://www.thedieselgarage.com/forums/showthread.php?t=57914&highlight=2+stroke+oil

Lubrication of ULSD is in theory the same as LSD, and the Cetane is not a problem either. The bigger difference is BTU or the energy in the fuel, Cetane is an anti-knock type number like Octane and does help it to run more quietly.

__________________

Gone to the dark side

- Jeff

Absolutely nothing. ULSD comes with additives from the start. No need to add any more. IF your seals do start to leak they were likely to leak anyways. Spend the $25 on a 30spline socket and $3 on new seals. You'll spend much more on additives than the cost of properly repairing it.

We don't even know what vehicle you have. 85 and older engines (OM61x) use copper crush washers instead of o-rings. The chances of them leaking is very small no matter the fuel.

aren't mercedes diesels supposed to leak?

In Theory.....NO

In Reality.....Damn near every one

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

A good lesson one my mechanic's friends had old crown vic the fan belts always made racket. We were all like why don't u fix that papaw he was like i like knowing there working if i can't hear them i know i'm screwed lol if it ain't leaking i'd be making sure i had oil in engine and fuel in the tank lol

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2004 Infiniti G35 3.5L 6mt Coupe 73K miles 25.6mpg ytd
2001 Green Audi TT 225 AWD Roadster 71K 6sp 30.9mpg >>STOLEN<<
1982 300D Turbo 231K 120hp? 28.1mpg YTD

This is one of the things that surprised me when I first joined this forum...there seemed to be little or no concern about ULSD and the effects it has on the vehicle! Go to any VW diesel site though, and comments fly thick and fast about these additives! In fact, most everyone swears by Stanadyne, which (according to some pundits) is actually required on VW diesels!

Having come from a VW that leaked like the proverbial cow on a flat rock, I was a little concerned. However, so far, I have not noticed any leaks on my IP. There is some new wetness developing on the top of my larger fuel filter (which was always dry before) but its not leaking in that sense.

Generally, I sense that ULSD hasn't really done much harm to the Merc crowd. It has decimated the VW crowd and a visit to any of the older VW diesel forums will show you how much angst those 4 letters have caused.

My question is: Why?

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1987 300TD
1984 300D
755,000 KM and going strong
BC Canada

Because our IP's are lubed via engine oil, VW's use fuel oil. ULSD seems to hasten the failure of a few old seals, thats about it.

Also lets not forget that for what my OM603 costs you can probably buy 3-4 VW diesel engines.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200