Let’s head down to the garage where Logan McCombs is tightening up some loose ends… to spec… on MotorWeek’s “Your Drive!”

LOGAN MCCOMBS: If you’re working on your car or truck, there will often be times when fasteners will have to be torqued to a certain spec, and sometimes in a certain pattern, to ensure that a part is lined up properly and tightened evenly.

An impact gun like this is great for loosening lug nuts and suspension bolts, but when tightening, it is always better to use a torque wrench. There’s less of a chance of cross-threading or stripping the threads, and with a typical impact gun, you really have no way of knowing how tight the lugs are. And if you’ve ever struggled on the side of the road to loosen a lug nut, you know that tighter isn’t always better! Over-tightening your lugs can warp your brake rotors, and lead to other problems.

To use a torque wrench, you preset the required number with a dial, which might be measured in foot-pounds for big bolts, and inch-pounds for smaller diameter bolts like oil and transmission pans, and valve covers. Your dial may also show newton-meters, which is an international standard unit for torque. Be sure to use the right wrench and the correct scale for whatever you’re tightening.

As you tighten the bolt, the wrench measures the amount of force being applied, and makes an audible click when that pre-set limit is reached. then you know the bolt is tightened just the right amount.

Another commonly stripped thread is oil pan drain plugs. Most oil pans are made of steel. Some are made of aluminum and more recently, plastic. On this Honda Insight, the oil pan is made of magnesium, which is lightweight, but is also a “soft” metal. After a number of oil changes, and removing and replacing the drain bolt, the threads on the bolt or the pan can become worn out or damaged, or even worse, the oil pan can crack just like this one did, and then you’re in for a very big repair.

To prevent this, you may be able to install a drain plug with a built-in valve, so that the oil can be drained without unscrewing the bolt and risking damage of the threads. While we’re talking about drain plugs, here’s one that has a strong magnet built into the end of it, so that metal shavings that circulate within the pan will stick to it and can be cleared off after every oil change. This is actually a great trick for extending the life of your engine.

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