Part Four: The Rear End
Moving under the truck, it was time to change out some other vital fluids. After looking at the fuel filter, I could only imagine the last time the rear differential was serviced. There is really not much to this job, and it turned out to be more messy than difficult. I opted to use Royal Purple for the rest of the fluids, because my editor did some dyno-testing in a previous issue and got a 5 hp gain by just changing the oil. I picked up a new gasket and a tube of RTV sealant to complete the job.

Part Five: Engine Oil
The engine oil and filter were next. According to Fra, the Tough Guard oil filter, which offers a 99 precent multi-pass efficiency, uses a combination synthetic glass and cellulose taht provides exceptional filtration for the life of the filter. Royal Purple's 10W-30 is made with the same blend of synthetic oils and the Synslide additive. I also picked up a new drain plug and oil cap.

Sport Truck Tech Tip
Some Fresh Air!

While I was under there, I decided to swap out the O2 sensor I got from Bosch. The O2 sensor is the primary measurement device for the fuel control computer in the truck to know if the engine is too rich or too lean. Because I had fuel problems, I decided to put in a new one for safety's sake. The new unit already has antiseize compound on the threads, so all I had to do was thread it in, tighten it up, and plug it in. Before you start the truck for the first time after installing a new O2 sensor, turn the key on to the run position for about 10 to 15 seconds to let the sensor heat up and burn off any contaminants.