Attention: TDR Forum Junkies 
Had a 2002 Caravan in the shop with a knock in the motor. Upon teardown I notice diesel in the fuel when removing the fuel line to get the intake off. Once in the motor I find the #3 piston hammered to death, this is a 3. 3 liter and #3 runs the hottest. Our car wash guy is a retired engineer from Texaco (wife told him to get out of the house or she'd kill him but that's another story). It seems diesel fuel has an octane rating of ZERO and will lower the octane of gasoline in direct proportion to the percent of diesel in the gas. 10 percent diesel lowers the octane 10 points. 5 gallons of diesel in a 20 gallon tank of gas lowers 87 octane to 62! The hottest running cylinder had no chance with all that pre-ignition, it hammered the ring lands closed and then washed down the cylinder and scuffed the piston and block to an early death. The engine is otherwise in great shape, no sign of oil stavation or coking.
Funny thing about diesel in gas is smell like gas until it evaporates a little. The light ends of the gas have boil off before you can smell the heavier diesel.
Funny thing about diesel in gas is smell like gas until it evaporates a little. The light ends of the gas have boil off before you can smell the heavier diesel.
