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Discussion Starter #1 (Edited)
Hey guys I want to take a few minutes and talk to yall about Fuel Dilution. Fuel Dilution is an issue in 2007 and newer light duty diesel trucks. Because of the Government and EPA, we have all seen first hand the increase in "eco" friendly diesel trucks. When we know in reality diesel is much more "eco" friendly than most gas motors, but they see things a little different.

The cause of Fuel Dilution in '07 and newer diesels trucks is the DPF (Diesel Particulate Filter). With the DPF you have what is called the regeneration process. This is where the computer tells the truck to allow unburned diesel into the cylinders on the exhaust stroke, thus causing and increase in exhaust gas temperatures to burn off the carbon build up on the filter. When this happens some of the fuel can run past the rings down the cylinder walls and into the crankcase causing Fuel Dilution. If this happens regularly (and most of the time its hard to tell when it's happening) the viscosity/thickness of the oil starts to break down. This is also known as shearing, where the molecular structure of the oil is torn apart.

When the oil starts to break down or shear it starts to lose its ability to protect your motor. Without the proper level of viscosity, the oil is no longer able to protect all the internal working parts, and handle the extreme loads we put on these trucks. Since diesel fuel is a natural solvent, it can reduce the life and lubricating qualities of the oil. Because of this it can increase wear, reduce fuel economy, increase repair bills, and possibly catastrophic failure.

Other factors that can lead to Fuel Dilution; frequent short trips, and long idling times. Both of these factors do not allow the truck to regenerate. Typically a truck that is driven long enough and gets to a normal operating temperature, and/or is used towing a lot will not regenerate as much, thus lessoning the possibility of Fuel Dilution.

In most cases less than 2 percent Fuel Dilution is unusual, but anything over 5 percent is a serious issue and needs to be addressed.

AMSOIL performed a Shear Stability test with Premium API CJ-4 Synthetic Diesel Oil (DEO), Mobil Delvac 1 ESP, Shell Rotella T, Chevron Delo 400 LE, and Valvoline Premium Blue Extreme. All of these oils tested were 5w-40, and were tested in an independent lab back in November of 2009. All of the oils were tested for Initial Viscosity with Shell coming out on top. Then each oil was tested for Sheared Viscosity with AMSOIL coming in on top. AMSOIL had the standards of the test doubled from 90 to a 180 cycles, then all the oil was contaminated at 2 and 4 percent Fuel Dilutions. At 2 percent Fuel Dilution AMSOIL DEO rated the highest in the Sheared Viscosity test, with Shell Rotella T being the only oil to fall out of the SAE 40 rating at only a 2 percent dilution. At 4 percent Fuel Dilution AMSOIL DEO stayed the highest in Sheared Viscosity while all of the others fell well below the SAE 40 rating at 4 percent. Thus showing that AMSOIL provided the best protection at 2 and 4 percent Fuel Dilution.

This test shows you first hand the importance of viscosity in your oil, as well as the ability for your oil to handle Fuel Dilution caused by DPF systems. You don't want to take the chance of running without adequate protection. Sure you change your oil every X amount of miles, but is your oil shearing before you change it? Without an Oil Analysis you really wont know what's going on inside, and if your oil is holding up.

If I can be of any help with this or getting you more information about AMSOIL products or Oil Analysis please feel free to PM, Email, or Call ramsdell or myself.

Click here to read the AMSOIL TSB (Technical Service Bulletin) about Fuel Dilution and see the Shear Stability Test results

Have a good day
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