- Car Care & Maintenance
How to Improve ULSD Fuel for your Diesel Vehicle
Owning a diesel vehicle offers great MPG for about the same cost as gas engines. Most VW diesel engines easily get 40-45 MPG on the highway and no less than 30 MPG in city driving. Diesel is just about at all gas stations. Modern diesel cars are clean versions of the old black smoking variety of the 1980's. Diesel cars are popular in Europe and now becoming the same in the USA. You don't need a costly hybrid for great MPG. Even 10 year old VW diesel cars still get 40-45 MPG. They make great first or second cars. But, there is a BUT, to all the accolades.
ULSD (Ultra low sulfer) fuel is the government's way of reducing air pollution and this fuel has only 15 ppm of sulfur, it replaced Low Sulfur fuel that had 500 ppm. That is a drastic reduction of sulfur. While it is good for the environment, it is bad for your car's fuel pump and fuel related items that needs sulfur for lubrication. Without the lubrication, the mechanisms wear out and scar much faster than normally.
The quality of diesel gas is hard to know and many feel that the diesel fuel lacks adequate lubricating properties. This is not the case in Europe where most diesel cars are. As emission regulations continue to become stricter, relying on diesel fuel producers is "iffy", because it is cheaper to make the fuel with less sulfur. Even the Cetane varies between 40-45 and most German cars prefer 48-55. Higher Cetane levels increase combustion for complete burning, it is similar to octane in gas. In Europe, most diesel is 50+ and premium diesel is 60. Oddly, only California has a mandatory Cetane value of 53 for this fuel. Another benefit of higher Cetane is better starting because higher Cetane levels ignites very easily under compression. Animal based biofuels have 55-60 Cetane levels and some have added small amounts to diesel for better lubrication.
In an independent test, most of the fuel additives for diesels were tested for scarring in a universally accepted test called HFRR. This test essentially uses a ball bearing in a solution back and forth on a metal surface for 90 minutes. The ball is then measured for scratches in microns. The result should not be more than 520 microns for US diesel fuel, although car manufacturers that make diesel cars prefer less than 460 microns, these are mostly German in origin. Less effective additives will causes scarring higher than 520 microns, which is bad.
The following products are the winners for best lubrication. If what you use is not on the list, stop using it.
- Opti-lube XPD
- FPPF Diesel Treatment
- Opti-lube Summer or Winter treatment
- Schaefer Diesel 2000
- Stanadyne Lubricity Formula
- Amsoil Diesel Concentrate
- Power Service Diesel Kleen + Cetane Boost (this is barely acceptable. Slightly higher than 530 microns)
- Stanadyne Performance Formula (this is barely acceptable. A little worse than #7)
Not recommended is Lucas Upper Cylinder or Marvel Mystery Oil. It should be noted that Volkswagen has its own additive made of polymers with a thicker viscosity. It is sold ONLY at VW\Audi dealers and you need to ask for it. The cost is $17. I use this in my VW Jetta TDI and there is improvement.