I'm new to diesels so I have questions. I have searched and read many posts on the topic of diesel purge. I am unclear, is this something that you only add to the main fuel filter when it is changed to 'clean out' the engine or is it something that can be added to the tank at fill-up?

What about other additives like gumout diesel fuel additive, do they keep the gunk (hate to use technical terms ) cleaned out of the tank and keep the fuel system clean in general?

Thanks in advance for all responses and advice!!

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1981 240D, Auto Trans, 160k miles -- CRASHED!

It is both.
If you want to really clean things out, run it straight. Run it in the tank for maintanence.

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

You will not get the full benefit of Diesel Purge if you just put it in the fuel filter. That will result in most of the product being "returned" to the fuel tank and diluted. To get maximum benefit, you need to engineer a closed loop where the purge gets returned to the feed container and recirculated. At idle, the engine will run 15-20 minutes on a can of purge.
You will need a couple feet of rubber fuel line and a container. You can use the original purge can, but a clear container is better. Connect one hose upstream from the fuel pump. Connect another at the return line. Put both hoses in the purge container. Run the engine until the purge is almost depleted. Make sure that the supply hose does not suck air.

I have been running Power Service diesel conditioner in the SDL. 12 oz. to 20 gallons. Cost is $2.00 per tankful if it gives you no fuel economy increase. But, with a 6 point Cetane improvement, it probably will give 1 mpg or so.

I don't ever need to bother with diesel purge.

Better to clean your engine all the time you are driving it then to do it once per year for 15 minutes or so.

Power Service is not in the same league as Diesel Purge. I used Power Service for years before I tried Diesel Purge. One can of Diesel Purge made a huge improvement in engine performance. If the color of the return fuel was any indication, Power Service leaves a lot to be desired. I have since switched to Stanadyne additive (instead of Power Service.) The improvement was very noticable.
On the down side, neither Diesel Purge nor Stanadyne is sold at Wal-Mart. Maybe that speaks volumes......

I did it by calculation so I might not be spot on. Hwever, I ramped my cetane up to 24 points increase and didn't see any mpg change.

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