Synthetic, unless you get that 5,000 high milage stuff, does not allow you to safely lengthen your oil change intervals. The additives still break down like the dino oil. Its the same as conventional oil, your engine is just more protected during these 3,000 miles. :biggthumpdakolorado said:I dont think its a free mod, especially if the oil cost 8 bucks a quart. The only thing you really get from synthetic oil is longer oil change intervals. Say 6000 miles instead of 3000. Dino oil has been around forever and has been used in cars and trucks for decades. I personally like to just change my oil and filter every 3000 miles. Just my.02 I had a car that had 200000 miles on the engine and nothing was ever wrong with it. It had the oil changed regularly.
And I'll add to the "free hp" Remove that rubber weatherstrip at the back of the engine bay in front of the cowl. This will allow air to evacuate the engine bay better, thus giving you a cooler engine bay. The rule is one hp for every 20* cooler under the hood.
Also, maybe its in a different place on the older trucks, but that rubber around the radiator on my '05 is to aide in cooling efficientcy for the radiator by directing more air through it. I removed some around the passenger side so my "Cold air" intake saw cooler air, but I'd recommend you leave the rest of it in place.