2007+ Diesel Emissions & Biodiesel; Not All That Rosy

In late 2007, the United States EPA diesel emission standards became much more stringent. The standard includes much lower sulfur levels, lower particulates, lower NOx levels, and a whole host of other regulations that’ll make your head spin.

As with any technology, there’s bound to be some bumps along the way and unfortunately, Biodiesel is one of them.

Ford, Chrysler, GM, Mercedes, Volkswagen, and a few other diesel manufacturers went to work on creating diesel engines that would be able to meet the new Tier II Bin 5 Standards. In initial testing it was thought that Biodiesel would help these engines to run cleaner (which it did), but unfortunately, because of cost-cutting strategies in implementing the new technology on the engines, all of the manufactures we’ve listed above have having MAJOR problems with Biodiesel in high blends. Here’s why….

The Diesel Particulate Filter (DPF) a.k.a. Biodiesel’s Worst Nightmare

– Picture from Diesel Power Magazine

In an effort to reduce particulates coming out of the exhaust of diesel engines, engine manufacturers mounted DPF’s into the exhaust pipe of the engines. The theory was that these honey-comb looking devices would entrap the diesel exhaust particulates (you know, that black smoke diesel make) and save them up to be burned off later.

– Picture from Diesel Power Magazine

To burn them off, the engine sprays some unburned fuel into the exhaust stream, vaporizes it, sends it down to the DPF where it ignites (because the DPF is already hot from heated exhaust) and burns off the particulates.

– Picture from Diesel Power Magazine

Sounds Like A Great Plan, Right? WRONG!
The problem all started when engine manufacturers, in their infinite wisdom, decided to use the same fuel injectors that inject fuel into the engine to inject a squirt of fuel into the exhaust stream.

They do this by squirting fuel into the cylinders shortly after the combustion stroke (called post-injection). The theory is that the already heated cylinder will vaporize the fuel and as the piston comes up from the bottom it’ll just push this unburned fuel out of the cylinder and down to the DPF.

In theory, this is a brilliant plan! Saves money re-designing the engine, the diesel fuel gets vaporized, the DPF gets cleaned & everyone is happy!

But What About Biodiesel?
Unfortunately, it doesn’t quite work that way with Biodiesel. One of Biodiesel’s strong points, the fact that it has a much, much higher boiling point than diesel fuel, just bit it in the butt!

The sad truth is that when the fuel gets squirted into that hot cylinder, only a portion of it vaporizes. The rest sticks to the walls of the cylinder like glue. As the piston comes back up, guess where the Biodiesel goes? Past the piston rings & right down into the crankcase oil.

“But I Thought Biodiesel Was GOOD For Engine Oil!”
Well, yes, but too much of a good thing can be bad…and in the case of the crankcase all that Biodiesel starts to add up & raises the oil level. If/when it gets too high, the rotating crank shaft starts to slap into the oil causing foam to occur and the next thing you know, the engine can go into hydro-lock. In other words, bad, bad things can start to happen to the moving parts. Another problem is that the oil, because it’d diluted with Biodiesel, can’t lubricate the engine properly so the moving parts have the potential to wear out much faster. Not good either! And, even if the oil DOES stay thick enough to lubricate everything, the Biodiesel still can reacts with engine oil additives and causes the oil to wear out faster; potentially causing even MORE problems in the engine.

So How Bad Is It?
It’s pretty bad. In fact, in tests performed by VW using B5 (5% Biodiesel/95% Diesel Fuel) in the fuel, in a matter of a few thousand miles over 40% of the engine oil was contaminated with Biodiesel. In Dodges running B20, engine oil levels increased in as little as 3,000 miles. Throw B100 in the tank and you can see where this is going.

So Whats The Solution?
1) DPF Delete Kits
If you’re lucky enough to live in a state or county where they don’t check diesel emissions or they don’t climb under the truck & check out your exhaust, you can simply install DPF Delete Kits which are available from many diesel performance shops. These kits include the parts necessary to remove the DPF from the exhaust system and the electronic parts to convince the computer that it’s not there anymore. Do this and the “regeneration cycle” never fires (that means the injectors never squirt that unburned fuel after the combustion stroke).

– Picture from Diesel Power Magazine

The problem with these kits is that technically they turn your rig into an “off-road use only” vehicle because it’s against federal law to mess with your emission system on your vehicle and drive it on a public road. That said, it hasn’t stopped hundreds of people from doing it anyway…

2) Change Your Engine Oil Much More Often
If you watch the engine oil levels and ensure that they don’t climb too high, then you may be able to get away with using high Biodiesel blends simply by changing out the oil more often (like twice or three times as often as the manufacturer recommends).

That’s kind of an expensive way to do it, but, it doesn’t violate any federal laws either

3) Don’t Buy A Newer Diesel Vehicle.
Stay away from anything about 2007.5 and newer and this problem doesn’t exist. Also, CAT figured out that if you install an injector IN THE EXHAUST SYSTEM ITSELF, this isn’t an issue (now why all the other manufacturers couldn’t have done that is beyond me).

Which Vehicles Are Effected:
Pretty much any diesel engine vehicle from about 2007 forward put out by GM, Ford, Chrysler, Mercedes, Jeep, Volkwagen, and Audi for sale in the United States is effected by this problem.

2011 UPDATE:
In 2011, GM added a fuel injector right into the exhaust stream and away from the cylinder. During the “DPF Regeneration Event”, fuel is sprayed directly into the exhaust, eliminating the problem. While they only warranty up to B20 in the engines, the oil dilution issue is a thing of the past (hint: I’ve heard it on pretty good authority from someone that works at GM that the Duramax can now burn B100 without major issues; granted, GM won’t warranty anything over B20 under warranty, but the engine can burn it if you’re willing.

2011 & newer Ford’s also now claim to be B20 compliant, however, unburned fuel is still injected into the cylinders so Biodiesel caused oil dilution may still be an issue. No word yet on how well they’ll do on B100. Caveat Emptor.

Where Can You Learn More?
Infopop Biodiesel Forum
This topic is being discussed at length in the popular Infopop Biodiesel Forum where Biodiesel specialists (myself included) are chiming in on what’s being done. Click here to see the discussion

Biodiesel Magazine
Biodiesel Magazine also did an excellent article on the DPF’s and how they’re effecting the use of Biodiesel. Click here to see the discussion

Diesel Power Magazine
Diesel Power magazine did an excellent article on installing Diesel Particulate Filters back in 2008. Unfortunately, the article appears to have been pulled down from their website for reasons unknown to me (probably worried about litegation, but go figure). If you subscribe to Diesel Power Magazine, it’s in one of their 2008 issues (sorry, I couldn’t remember which one. It’s in their Tech section).

I really hope that the manufacturers get this issue solved; and solved quickly because if they don’t, it could spell an end to the use of high blend Biodiesel in newer diesel engine powered vehicles.

If you plan to purchase a newer diesel vehicle and run Biodiesel in it, we encourage you to research the issues as much as possible and to be sure you’re aware of any of the limitations of high-blend Biodiesel use in the vehicle you choose.

About Utah Biodiesel Supply

Utah Biodiesel Supply is an industry leader in offering innovative ways to empower our customers to produce Biodiesel. From free online instructional videos on how to get started making this great renewable fuel to promotional items to help our customers proclaim their energy independence, Utah Biodiesel Supply has it covered. With the widest selection available of Biodiesel equipment, supplies, and promotional items, you're sure to learn something new about Biodiesel every time you visit.

13 comments on “2007+ Diesel Emissions & Biodiesel; Not All That Rosy

  1. I had no idea that there was this problem. I own a 2009 diesel truck. I have a dpf delete kit installed, but I did not know the significance of it. I think that just about every truck in my area has one of these. If I ever buy a new truck or car again, I will have to make sure that there is a kit on it.

  2. Yep. It’s a really big issue. Getting that DPF out of there will really benefit you in the long run too. The truck can breathe a LOT easier, which means you get more power to the wheels and get increased gas mileage (because you’re not wasting fuel cleaning the DPF).

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  4. Hello Guys,I´m a small scale biodiesel home made producer from Madrid -Spain and after reading the biodiesel comments about the problems caused on diesel engines I am a little bit worried about how this home made biodiesel could affect my 1997 Peugeot 806 van and also my 2007 ML 320 Mercedes SUV , in which I am blending higher Biodiesel percentages than 5%.
    I am using only WVO from homes and restaurants and as you probably are aware most of our cooking procedures in Spain are made with Olive oil, so please let me know what should be the potential problems in these vehicles.
    Thanks in advance.

    • I would think the 97 won’t have any problems at all. You’ll want to check & see if your 2007 has a Diesel Particulate Filter (DPF) on it though. If it does, you’re going to need to be extra careful running high blends in it. But if it doesn’t, it should run in the Mercedes just fine.

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