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Old 03-17-2004, 08:08 PM
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I have monitored this list for a while now, but have not seem much relative to fuel additives. The exception is during extreme cold to keep the fuel from turning to gel. Of course, MB seems to recommend against them, or at least that is what the fuel filler door states. What is the deal on additives? Are their diesel additives that should not be used in Mercedes? Who uses them year round versus just in winter?

Do they do any good?

Alan Hamm
'87 300SDL 277K Miles
'89 560 SL 68K Miles
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Old 03-17-2004, 09:03 PM
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The late 70s and early 80's MB diesels were designed to run on diesel fuel with a minimum cetane of 45.

Diesel fuel cetane ratings in America has steadily decreased from nearly 50 in the 60s, to 45 in the 70's and early 80's to around 40 or 41 common today. This is really too low for our diesels.

Adding cetane boosters can improve how smoothly the engine runs, and, by some accounts, can improve fuel economy to such a point that the additive pays for itself twice over.

Either way, if you do add something to the fuel, make sure it's a legitimate diesel fuel additive. Don't add anything like motor oil, or transmission fluid, and never try to burn up that used motor oil in your tank. Big Bad MOJO.

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Old 03-18-2004, 01:00 AM
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Try Biodiesel as an additive.

Biodiesel has a higher felt cetane rating than any petro diesel fuel you'll find and is higher than #2 diesel WITH cetane additives.

Cetane #'s for BD are in the 46-60 range, depending on base-stock.

It's a VERY aggressive cleaner and will require a few filter changes when you first start running it.

Substantially lower soot production (my oil stays honey colored for almost 500 miles after a change) and lower particulates are more of the benefits. Something like 47% less soot than #2.

Oh yeah, and lubricity is substantially higher than #2 diesel.

Best of all, it only costs a little more than #2 diesel making it cheaper BY FAR than any additive you could find (~$2.75 GALLON as opposed to $2-5 per QUART for additives!)

Downside: Gels at a higher temp than #2 so Arctic Express is the usual cure in the winter or a blend with #1 diesel (Kero)

Also will attack rubber lines in time (not the modern lines that are a Viton blend, but the older Merc lines) and you'll need to change the flex lines to more modern mat'ls.

One tank now and then will not hurt anything, it does take long-term exposure to damage the rubber.
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Old 03-18-2004, 01:46 AM
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Even though MB does not recommend fuel additives, they do say to add kerosine to the diesel in the winter time, if winter grade diesel is not available. I use Power Service diesel additives. $4 gets you a bottle that is good for 100 gallons. They have winter and regular formulas. The winter one prevents diesel from geling. Both formulas increase the cetane level in the tank.
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Old 03-18-2004, 02:07 AM
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Howes Diesel Treat

Is what I use 365 days a year and have had NO fuel related problem.
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Old 03-18-2004, 02:42 AM
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This is what I use as a fuel additif ( Marly CTi ).
I use it for almost 30 years now. It changed 2 times of name and maybe composition too. But it's still very effective!
Further I am using the radiator lubricant and additives in engine and rear axle gear. Not in the autotranny : it would cause slip !

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Old 03-18-2004, 08:43 AM
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Originally posted by TomJ [/i]
[B]Try Biodiesel as an additive.

A while back someone was going to post how it was you find biodiesel. I never see places that have it.
Alan Hamm
'87 300SDL 277K Miles
'89 560 SL 68K Miles
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Old 03-18-2004, 09:00 AM
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Old 03-18-2004, 09:14 AM
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Oh Well

That bites. The closest place is over an hour away. Thanks for the link.
Alan Hamm
'87 300SDL 277K Miles
'89 560 SL 68K Miles
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Old 03-18-2004, 09:54 AM
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Another option

You can look into Waste Vegatable Oil, ie: fryer grease. There are several comments on this. I believe it also has cleaning properties. Besides, it's usually FREE!!! Try this link.
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Old 03-18-2004, 01:18 PM
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Additives in general should not be required and might even cause a little harm if used constantly (like, every tank). I do use a little once in a blue moon (maybe annually, if that) and only products from reputable companies. The two I prefer are Red Line and Stanadyne. Never use ATF!

Biodiesel is neat stuff if available - I didn't know of any stations with it here in Boise, until I tried Tim's link! Hmmm, that's not far from me, I might try a tank:

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Old 03-18-2004, 03:18 PM
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My mechanic, who runs a fleet service handling lots of diesels of all brands, suggested using a mix of 50:50 Diesel Service cetane booster and Marvel Mystery Oil, 8 oz. every thiird or fourth fill up. It seems to pep up the engine, and also quiets it a bit. Been doing it for over a year now with no problems. The car starts easier too. He swears by it, and has several very high mileage customer diesels that seem to prove it.

You can buy the large (1/2 gallon I think) containers of each in any good auto store- Pep Boys is cheapest in my area.
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Old 03-18-2004, 03:48 PM
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Been using power service for as long as I've had diesels. Good stuff, seen more often on store shelves than anything else it seems. I'd like to experiment with some MMO added in or some ashelss 2cycle oil for it's lube ability..

Say what you want, ATF was a wunnerful additive until they put all that crap in it..
I'd give a lot to find a cheap source of plain jane ATF again.
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Old 03-18-2004, 04:18 PM
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I always value your insightful input in these discussions. I am wondering if you could expand on the concept of continual use of additives being potentially harmful?
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Old 03-18-2004, 04:51 PM
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I mostly got that from listening to Dr. Booth repeat it over & over. The idea is that a properly running engine, with a clean fuel system, should not need any additives. Also, sometimes the additives can leave deposits if used too frequently or in too high a concentration, or at least that's the theory. There is often no measureable benefit in MPG either - if so, something is WRONG and needs to be fixed (IMO). I had been using some Red Line 85+ in each tank, but quit after hearing Doc's mantra, and whaddya know - there was no change in anything when I stopped using it! Good clean diesel, from a popular filling station (one that moves a LOT of fuel daily), is generally the best thing you can feed the car (well, except BioD, but that ain't cheap.)

Again, if you do use additives, I recommend a diesel-specific additive, not a MMO type item... read up on Stanadyne's website for some interesting information. I like their products a LOT but they're not particularly cheap, or easy to buy locally (mail order is OK).

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