If there's any kind of slimy...
If there's any kind of slimy feel, scale, bad color, or funky smell to your truck's coolant, skip testing it and move right on to using a good radiator flush, such as Prestone's Super Radiator Flush.
That old adage "an ounce of prevention is worth a pound of cure" is true, and when it comes to your truck's cooling system it only takes 22 ounces of radiator flush, plus a couple gallons of antifreeze to save yourself from a ton of trouble and expense in the future. Even for a classic truck that sees only a little bit of use in the summertime, and then sits parked in a warm garage all winter long is subject to extensive damage caused by rust and corrosion. Who among us at one time or another hasn't had their weekend cruise ruined because a rusted-out freeze plug let go in the hardest part to reach, or a water pump sprung a leak? Starting at the radiator, entering the engine through the aluminum thermostat housing, every metal in the entire cooling system that gets wet is subject to damage. Throw a set of aluminum alloy heads on top of a cast-iron block with an aluminum intake manifold, and that's a guarantee. In the case of an expensive engine with rare parts or even for someone who just wants to make sure their truck is ready to roll when the weather is right, flushing the cooling system and topping it off with the right concentration of antifreeze is cheap insurance. Notice we said the right concentration of antifreeze, that's because too much can be almost as harmful as not enough. Thanks to the folks at Prestone, determining whether or not your cooling system has the right amount of antifreeze coursing its veins only adds around $6.00 to the total expense. The device resembles a hydrometer used to test specific gravity in an automobile battery, and works in much the same way. The black rubber bulb is squeezed and then let go to suck in enough antifreeze to fill the tester's chamber all the way to the line at top, and then the red needle will point on the scale to indicate the reading. On one side the scale indicates the boiling point, and on the other side freezing. In addition, the Prestone tester's clear-plastic construction allows a visual inspection of the coolant to look for rust and contaminants. Indications of a rust color mixed with a pale green solution and metallic flakes means you are a neglectful owner and your truck should be taken away from you. No, we're just kidding, but it is time to do something about it before severe damage occurs, if it hasn't already.
 The first step with the engine...  The first step with the engine cold is to completely drain the cooling system into a container and dispose of it properly. Do not pour used antifreeze onto the ground or allow your dog to drink it. Dogs like the sweet flavor, but ingesting antifreeze will kill them. |  In the area of only $6.00...  In the area of only $6.00 Prestone sells a back-flush kit that makes servicing one's cooling system fun again. The kit includes three different fittings to fit most popular applications. |  It's best to install the T-fitting...  It's best to install the T-fitting away from the engine's distributor and/or ignition coil to prevent direct exposure to water. A single slice allows the T-fitting to be installed into a heater hose corresponding with the T-fitting's indicated size. |
 This yellow-and-black adapter...  This yellow-and-black adapter screws onto the end of a garden hose and then is connected to the T-fitting. With the heater valve turned on high and the engine running, the water pressure is turned on high enough to maintain a constant flow. |  A yellow plastic gooseneck...  A yellow plastic gooseneck is included to direct the back-flushed water from the radiator header tank away from the engine compartment. The last thing you'll want is the exiting water hitting the fan blades. |  Once the system is flushed...  Once the system is flushed clean, this black cap is screwed on snugly and the T-fitting is left in place, which makes the next time you back-flush even quicker to do. |
 For around $6.00 this handy...  For around $6.00 this handy device is usually sold in the same aisle as Prestone antifreeze and Prestone radiator flush and allows one to verify they have a proper concentration of antifreeze in their cooling system. |  To demonstrate how the tester...  To demonstrate how the tester works we first filled it with plain water and discovered plain water offers little or no protection from freezing as confirmed by the red indicator needle. |  Next, we flipped the tester...  Next, we flipped the tester over to the other side and tested plain tap water for its ability to resist boil-over. If the water contained a slight amount of antifreeze it would have been reflected in the reading. |
 The recommended mix of antifreeze...  The recommended mix of antifreeze and water is half and half (50/50). This photo shows our results, mixing the Prestone antifreeze equally with water provides maximum protection from boiling over. |  We then flipped the Prestone...  We then flipped the Prestone antifreeze tester over and observed the 50/50 mix provides maximum protection from freezing as well. |  Thanks to being 100 percent...  Thanks to being 100 percent compatible with all makes and models, one only needs to keep Prestone Extended Life antifreeze coolant on hand to service every vehicle owned. To obtain a proper 50/50 mix look up your truck's cooling system capacity in a shop manual. |