Here it is straight from Chevron;
I accidentally mixed gasoline with my diesel. What can I do?
One percent or less gasoline will lower the flash point of a gasoline/diesel fuel blend below the specification minimum for diesel fuel. This will not affect the fuel's engine performance, but it will make the fuel more hazardous to handle. Larger amounts of gasoline will lower the viscosity and/or cetane number of the blend below the specification minimums for diesel fuel. These changes can degrade combustion and increase wear.
The best course of action is to recycle gasoline-contaminated diesel fuel back to your supplier. People ask if they can correct the problem by adding more diesel fuel to the blend. Usually the answer is no; the amount of additional diesel fuel needed to bring the flash point on test is impractically large. Those who try dilution should have the blend checked by a laboratory before use to be sure it meets specifications.
I accidentally mixed gasoline with my diesel. What can I do?
One percent or less gasoline will lower the flash point of a gasoline/diesel fuel blend below the specification minimum for diesel fuel. This will not affect the fuel's engine performance, but it will make the fuel more hazardous to handle. Larger amounts of gasoline will lower the viscosity and/or cetane number of the blend below the specification minimums for diesel fuel. These changes can degrade combustion and increase wear.
The best course of action is to recycle gasoline-contaminated diesel fuel back to your supplier. People ask if they can correct the problem by adding more diesel fuel to the blend. Usually the answer is no; the amount of additional diesel fuel needed to bring the flash point on test is impractically large. Those who try dilution should have the blend checked by a laboratory before use to be sure it meets specifications.