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Originally Posted by blue7.3
Regarding ULSD lubricity, I've read so many different theories on that. But I run PS octane boost w/ their version of lubricant in the summer just in case.
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You mean cetane boost, right? Octane would be for gasoline engines, not diesels.
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I imagine AMSOIL has a version of that product also? How does it compare?
cheers,
-pete
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AMSOIL's summer diesel additive is
AMSOIL Diesel Concentrate.
Cetane lowers the flash point of diesel fuel. It doesn't really add any energy or Btu content to the fuel. In the winter, cetane is advantageous since it makes diesel fuel easier to ignite at lower temperatures. This also improves combustion, which is good for minimizing incomplete ignition/combustion that results in cylinder wash down. Cylinder wash down in a diesel means that the unburned (incompletely combusted) diesel fuel washes down the cylinder walls, causing piston ring lubricity to suffer, which can lead to cylinder wall scoring and ring deterioration. It also leads to oil dilution (fuel contaminating oil) which deteriorates the oil's TBN (total base number) and lubricating properties.
Getting back to Cetane, since it lowers flashpoint, is an additive that is overused and misunderstood. In warmer months, especially when towing where cylinder temps and exhaust gas temperatures can be between 1,100 and 1,400 degrees Fahrenheit sustained, cetane can do a disservice. Lowering the flashpoint of diesel fuel in these high temperature situations can cause preignition (fuel combustion before the piston reaches top dead center, or TDC). This can cause a drop in power, a drop in mileage, and excess piston face stress. In an extreme case, usually in modified engines, this can promote piston failure, which inevitably leads to engine failure. I know Cetane is advertised as a power enhancer, and people tend to over treat with it quite a bit in my experience. For this reason, AMSOIL's Diesel Concentrate does not include a Cetane Booster additive. AMSOIL offers a separate product,
AMSOIL Cetane Boost, as a stand alone cetane additive. This leaves the end user the option of adding or not adding cetane to their fuel depending on ambient temperature, engine demands and operating temperature, and fuel quality.
Running Power Service with Cetane Boost will not cause your engine to fail. My example above is an extreme case, in a modified diesel engine with gross over treatment. But, if you're paying money for a cetane boost that is causing you to see a drop in rear wheel horsepower and a drop in mileage, wouldn't you like the option to omit cetane additives during the warmer months?
-Chuck