Buying a used diesel truck is a big investment, so before laying down some serious cash, you'll want to make sure that what you're buying is up to snuff. Read on below for four tips to keep in mind when you start looking to buy a used diesel truck. 

Tires

When it comes to tires, you shouldn't ever be afraid to get up close and dirty. That's because a close inspection of a diesel truck's tires can reveal a lot about how the truck has been driven, for better or worse. Look for regular tread wear patterns--in other words, patterns that don't indicate too much wear on either the inside or outside of the tread. Irregularities in the tread wear are often a sign that the vehicle has improper alignment or has been carelessly driven in the past.

Fluids

When it comes to diesel trucks, you'll want to inspect two different types of fluids: coolant and oil. Coolant should never be colorless; rather, it should be a bright red, green or blue. Some coolants are also slightly yellow in color, but never clear. If you notice small pieces of debris in the coolant, that's a sign it needs to be replaced soon. Problems with the engine can also cause the oil to appear as a milky white substance, so make sure that there no such streaks when you check a used vehicle's oil. 

Exhaust

One of the main things that differentiates diesel trucks from non-diesel trucks is that diesel trucks emit a slightly thicker exhaust smoke. That said, the exhaust coming from a used diesel truck should never be a thick black color or - even worse - white. When the vehicle isn't running, you'll also want to get a closer look at the exhaust itself, and check to see that there is not a huge buildup of soot inside. A significant amount of soot can spell problems for the exhaust system in the future.

Engine Startup 

Arguably the most important part of any used diesel truck is the engine. Diesel trucks are a bit harder to start up in cold weather, so if you get a chance, check out the trucks you're seriously considering purchasing on a cold day, in order to test how the engine performs when started up for the first time. If you notice that the engine takes a long time to turn over, you may want to look elsewhere. 

Keep these tips in mind as you begin checking at trucks from dealers like Arrow Truck Sales.