Ive mentioned my 2001 GMC pickup truck on many occasions. Its an extended cab, stepside bed with a lot of really nice features. It has a 4.8 liter (292 cubic inch) V-8 engine, good automatic transmission and Positraction differential. It also has a great beast of an air conditioner system, power windows and locks, excellent sound system and even tinted windows.
I say all of this to preface the fact that I sold it last month to a guy from San Diego. He wanted it to pull his boat to Lake Havasu, Ariz. He was very happy to get it since it is a very clean, reliable – never had any work done under the hood – and comfortable ride.
Why did I sell it? In the last two years or so, I had driven it less than 9,000 miles. I know this because I bought new tires for it two years ago and the warranty noted that there were 89,000 miles on it.
When I sold it, it had reached 98,000 miles and the things that normally happen to older vehicles were beginning to catch up with it. Three items deserve special attention: The power windows didnt work (the regulator was shot). The mode controller, which sets which way the air blows from the air conditioning and heater system, was really touchy and would make what could only be described as a slapping sound if you didnt set the control just right. The tailgate latch had lost a plastic retaining clip and wouldnt work.
At this point, youre probably asking yourself, so what? Well, there are some facts about this truck that you might find of interest. When we think of lubricants for vehicles, the big three – engine oil, transmission fluid and gear oil – are the ones that come to mind immediately. Some folks remember the power steering fluid, and a few might also mention grease. But did you know that there are a bunch of other lubricants that are needed to ensure that your vehicle runs properly and your creature comforts are fully realized?
In the case of this pickup, the grease that lubricates the power window regulator ensures that the window will work properly whether you are in Minneapolis in January or Death Valley in July. Needless to say, this could only be a synthetic grease with extreme-pressure capabilities as well as antiwear, rust and corrosion resistance. It needs to have a long service life (mine lasted about 10 years). Fortunately, in my case the power window failed in the closed position so the only difficulty was in going through the drive-through at In-N-Out!
Another problem with the pickup was the mode controller. This is a complex electrical switch that changes the direction that air flows from the heater/air conditioning system. In cold weather, warm air is desirable on the floor, while in the summer months, air conditioning feels better when blown through the dash vents. In addition, air needs to blow over the windshield to defrost and de-fog the glass.
An electrical grease is required that works over that wide temperature range and lubricates the mechanism as well as the electrical contacts, without forming debris that will cause the switch to malfunction. The choice of the lubricant components is very important, as some base oils may form too much debris in the presence of electrical arcing.
Another area where a specialized grease is needed is in the door lock mechanism. Again, the wide temperature range is critical to long life and satisfactory performance. There are electrical switches in remote locks that need proper lubrication, to assure smooth motion and low frictional characteristics. These products are also used in many multifunctional switches, power window switches, even power mirror switches. There are so many switches that we dont even consider, including ignition, hazard warning, headlamp, power seat, fuel cap and trunk release.
One very specialized lubricant is for the airbag rotary connector in your steering wheel. This switch, which looks somewhat like the main spring in a mechanical watch, is commonly referred to as the clock spring. Since one of the primary safety features of modern automobiles is the airbag, which for the driver is located in the steering wheel hub, you definitely want it to work. As if that werent crowded enough, there are a number of other contacts found in the steering wheel, including the horn, cruise control, radio tuning and others.
To be sure youre getting the best performance out of these contacts, youll want a lubricant that can operate efficiently through a wide range of temperatures; meet torque/force requirements for the steering wheel; be composed of the proper types of components; and be relied on to not separate. Naturally, this is a grease, since it needs to stay in place for as long as possible.
When you move a switch, either by turning or sliding it, you want the movement to be smooth, relatively easy and quiet. Thats obtained by using what is called a damping lubricant. Just think of the number of switches and mechanisms in your vehicle that function by sliding or turning. A variant of this is the so-called smooth feel lubricant. This can be anywhere in the vehicle. In the case of my GMC, a good smooth feel lubricant might have helped the tailgate latch to work better, and surely longer. As it was, I had to periodically take the latch apart and re-assemble it in order to get a few successful openings and closings.
I could go on with the large number of specialized lubricants in a vehicle. Others that come to mind are ignition switches, seat adjustment rails, and hood latch and spring mechanisms, as well as tailgate lubricants. The fact is, any vehicle is a moving collection of all types of petroleum products – some oils and a lot of greases.
At this point, I cant help but bring up the big players in vehicle lubrication: engine oil, transmission fluid, gear oil and grease for the various major vehicle lube points. We all know that light-duty vehicle engine oil is designated by API Service categories. Certainly by now everyone understands that engine oil chemistry changes regularly to meet new, usually more stringent requirements from the OEMs. Backwards compatibility describes the fact that the most recent oil category will be satisfactory for servicing earlier engines. The rationale is clear: Newer oils offer better protection and performance, which makes them completely compatible with older engines and specifications.
Gear oils are similar, in that almost all axles use an industry standard API category GL-5. There might be a modification for limited slip differentials, but it would also be based on GL-5 performance.
Grease has its own category system defined by the National Lubricating Grease Institute that describes the required performance for various bearing applications. One of the largest applications is constant velocity joints. They are the connection between front wheel drive transmissions and the wheels they drive. These joints must provide power to the wheels and at the same time allow the vehicle to turn easily. Such greases are designed for pretty wide temperature range performance and must be chemically compatible with the elastomer boots that fit over the joint to keep it clean and dry. For other applications, such as wheel bearings or general chassis lubrication, the choice should be an NLGI licensed or OEM specified grease that is designed for each use. I know its a pain to inventory more than one grease, but doing it right the first time is always the safest path.
Automatic transmission fluid is a lot more confusing, since each major OEM has its own requirements. My pickup still had its original, factory-fill Dexron III(H). Its important to make sure the transmission lube is the exact one that the particular OEM has blessed. (If I had needed to replace my ATF for some reason, for example, a fluid meeting GMs Dexron VI spec would have been my sole option now.) Some much-older vehicles recommended using ATF for power steering, but that hasnt been the practice for quite some time.
Getting back to the beginning, the GMC is on to a new life that sounds like a lot more fun that hauling yard debris to the dump. Well have to figure out how to move the occasional piece of furniture in the 2008 Nissan, which shouldnt be too hard as long as it isnt a three-piece sectional.
Im now on the lookout for a good deal on a vehicle. Dont know what itll be or when Ill get it, but I hope it is just as reliable as my old ride.
Industry consultant Steve Swedberg has over 40 years experience in lubricants, most notably with Pennzoil and Chevron Oronite. He is a longtime member of the American Chemical Society and SAE International, where he was chairman of Technical Committee 1 on automotive engine oils. He can be reached at steveswedberg@cox.net.