Can’t afford that brand-new, top-of-the-line diesel truck? We know how tempting it can be, and how hard it is to say no. But that doesn’t mean you can’t find something great out there that’s new to you. When you find that perfect vehicle that’s just within your budget, driving it home can feel like you just won the lottery.
 
But as with any lottery winning, you have to be careful that you don’t get more trouble than you anticipated. It’s no different with a used diesel vehicle – you don’t know if the engine looks good on the inside, if the parts are clean, or if the fluids are topped up. So why take the chance on breaking down before you even get a chance to really enjoy your new ride? Here are the top 4 things to do when you buy a used diesel truck, to make sure you stay on the road and moving fast.

Tuning a diesel engine with switch-on-the-fly (SOTF) tuning is a longstanding trend that has been going on for many years in the industry. With plenty of after-market parts and options to choose from, it has historically been rather easy to change up the power potential of your truck, allowing for more or less torque and horsepower depending on the job at hand.
 
So what is SOTF tuning? Up until 2011, Duramax powered diesel trucks could have an upgrade installed called a DSP5 (Duramax Switchable Position 5). This upgrade began with an update to the electronic files in the Engine Control Module, using a custom EFI LIVE operating system, and was accompanied by a dial wired into the dash that allowed the driver to choose between five different settings (as pictured on this page). As this dial was turned, the ECM would change tune files in the operating system, changing the fuel pressure maps, throttle maps, etc. to match the setting and give more or less power to the engine.