Reader Question: The Hair in the Diesel Soup?

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Here’s the latest reader question, along with my reply!

Tim asks: Always love your articles. One point not addressed in your recent piece about apocalyptic diesels is the cost of the go-go juice. Maybe a follow up article on the price of diesel go-go juice would be warranted. Why does diesel now, in some states, like mine (CA) cost more than premium fuel? They surely can’t claim it costs more to refine – although they may try to. My guess is the slowly want to phase diesels, and may us too, out. So why not make it unattractive, price wise; not performance wise? Please enlighten us.

My reply: A few years ago, a mandate – yes, another one – was passed that all road-going diesel fuel be Ultra Low Sulfur (ULS) and this has caused the spike in the price of diesel – not just in CA but nationally.

However, there’s some good news still.

The first is that it’s possible to make your own diesel – and it’s a lot cheaper than the pumped stuff, especially since it’s also free of the taxes applied to the pumped stuff. Newer diesels may require some mods to overcome their emissions rigmarole – but it’s no worries in the older stuff, which hasn’t got the rigmarole.

Another end-run is to acquire off-road diesel, which isn’t ULS – and costs a lot less. This is sold at most places that sell road-going diesel. Of course, you’re very much not supposed to put this fuel  – which is dyed red – into the tank of a road-going vehicle and the store will raise a ruckus if they see you doing it, not because they object but because they want to avoid being Hut! Hut! Hutted!

That said, one could certainly fill up a 50 gallon drum in the bed of one’s truck for one’s tractor back at the farm. . . .

. . .

Got a question about cars, Libertarian politics – or anything else? Click on the “ask Eric” link and send ’em in!

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  1. Well, the diesel nazis are thick in Texas. You don’t want to get caught with red in the fuel. Last people I knew just let the truck go rather than pay 50 or more cents per mile for every mile on the odometer. I used to use farm diesel every once in a great while but didn’t make a habit of it, just if I was empty and had some farm diesel handy. I don’t think I’d even put 5 gallons in now days. And you damned sure don’t want to put in anything with farm tags or obvious extra tanks. Even if you use the extra tank type tool box, you certainly don’t want farm diesel in it.

  2. Don’t know about other places, but where I am, off-road diesel is literally only pennies cheaper than road diesel these days.

  3. Hi Eric–to clarify-the reason you don’t want to run higher sulfur Diesel fuel in a piece of equipment with a D.O.C. (Diesel oxidation catalyst) and a D.P.F. (Diesel particulate filter) is that the sulfur will contaminate the substrates similar to what lead does to a catalytic converter. The DOC has reduced efficiency, DPF then gets plugged up and when the ECM tries to do a “Regen” (high temp burnout of the soot using extra fuel injected into the exhaust in the DOC) the temps don’t get high enough to turn the soot in the DPF to CO2, water and ash and the engine derates to the point where the truck is limited to 5 mph. Engines equipped with SCR (selective catalyst reduction) are subject to the same thing as they have DOCs and DPFs also. If the filters and catalysts are damaged beyond repair the replacement costs get into the multiple thousands of dollars range. As I work as a Diesel mechanic I’ve seen what these poor drivers and owners have to pay to get their truck back on the road. Your best bet is to run ULSD fuel on trucks with the aftertreatment systems in place or remove it all and run whatever fuel you’d like. I’ve heard of guys deleting the EGR, DOC and DPF, but since I work at a truck dealership I don’t see it. What I have seen is is other shops running 1″ drills through the substrates of DPFs thinking they’ll ‘fool’ the ECM –doesn’t work as the ECM sees the difference between the inlet and outlet pressure of the DPF –if it’s too low the ECM ‘knows’ the DPF is compromised or has been removed and derates the engine. If the customer then tries to replace the DPF and put the aftertreatment system back to stock they’re shocked to find out the drilled DPF has no core value–there goes up to $2000…..up in smoke. Again–better off leaving it stock or removing it all. Better yet-get an older truck, choose your favorite engine and trans combo, fix it up and run it. If I was a owner/operator I’d like a Detroit Diesel 8V92 DDEC III with an Allison behind it in an International 4300 TranStar Eagle.

  4. What’s the difference between red & ULS diesel? Even my tractor (a diesel Kubota bought in 2011) has a sticker advising to use only ULS. Is any diesel motor harmed by using red?

    • Hi CW,

      Off-road (red dyed) diesel has higher sulfur content, which older diesels need; the sulfur improves the lubricating properties of the fuel which lubricating properties accounts, in part, for the usually much longer life you’ll get out of a diesel engine.

      For emissions reasons sulfur content has been reduced in on-road diesel, which probably will result in reduced service life (as well as higher cost, for the ULS).

      Using the off-road stuff in a diesel-powered vehicle designed to use ULS will increase its emissions but shouldn’t result in any harm to the engine. It’s not like using leaded regular (if you can find it) in a gas-powered car designed for unleaded – which will foul the catalytic converter in short order.

      Diesels don’t have cats. They have particulate traps/urea injection – neither of which should be materially affected by the use of higher-sulfur content fuel. If anything, the higher-sulfur content fuel will help your engine run longer – much to the dismay of Uncle!

      • The red-dye diesel may or may not be ULS, at least out here in Texas – I add the diesel lubricant just in case. The biggest difference is the lack of road taxes.

        Got to be a pain to buy dyed diesel here in the Austin area. Last couple of times I just filled up the 55 gallon drums at the local grocery store, as my regular dyed diesel station (as well as any other I found) switched to “account only” sales, and the hassle wasn’t worth the small savings.


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