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Diesel Fuel Additives

I have a new 2009 VW Jetta TDI. I ran into someone who said that they use a fuel additive in their diesel and it improved their mileage significantly as well as reducing the frequency of fuel filter replacement (Apparently that was a problem with their car that the dealer could not resolve - not a VW). I wonder what your opinion is about using diesel fuel additives in a new car? Do you think it would void the warranty? What is the downside, other than the extra cost? Do you have any specific additive brands you would recommend if you think it is helpful?

There are over 100 different flavors of “Diesel Magic”. They all claim miraculous benefits. Which flavor are YOU considering?

When purchasing a new vehicle, follow the recommendations in the owners manual. And until the vehicle is out of warranty, then you can expieriment with fuel additives.


If this stuff worked, don’t you think they’d be making billions selling to the long-haul truckers? Anything’s possible, but there hasn’t been one that works so far…

It works, but nothing like “improved their mileage significantly” or “frequency of fuel filter replacement”

You can expect minimal fuel milage increase and I would strongly recommend not extending fuel filter extension, as that can cause the need for a new fuel pump.

“what your opinion is about using diesel fuel additives in a new car?” The same as the use in an old car. All the additives that are needed are already in what comes out of the pump.

“Do you think it would void the warranty?” As long as you use a major product and follow the instructions, it should not void your warranty.

Generally it is a good product looking for a problem that seldom exist.

In the fall when the temperatures are starting to go down below freezing it might be a good idea to use one or two bottles, following directions, to assure that you have winterized fuel in there just encase you get a really cold spell. (same thing if you live south and drive north in the winter.

“What is the downside, other than the extra cost?” None and you might regain a part of the cost with the slight mileage increase.

I use Stanadyne, winter formula each fall and that is about it.

For a lot more information and opinions visit

In the most part all fuel additives are a fix looking for a problem and few people really need them.

If VW finds out you’re using a fuel additive the warranty will be tossed out the window. Read the warranty. You’ll see.

Your VW is designed and built with the latest in clean diesel technology. Don’t try to out-think the factory engineers. If they wanted you to use an additive, they’d tell you to use an additive.