if you are worried about the sludge before changing your oil drain a quart and a half out add a quart and a half of paint thinner or kerosene,paint thinner work better,let the car idle for 5 or 10 mins.drain oil replace with oil of choice.i dropped my oil pan and clened it out good also.i put royal purple in mine runs great.

my truck will run fine then suddenly die on me,all the dash gauges fail except for the digital,i get a code on my odometer that reads No Bus.I have already replaced the coil pack,after sitting for sometimes hours it will start and run fine till the same thing happens again,which could be 10 mins.up to 3hours  one time HELP