Oils and Filters: Selecting the Correct Lubrication and Filtration

Order Reprints
Oils and Filters: Selecting the Correct Lubrication and Filtration

The importance of oil and air for the proper functioning of your customers’ vehicles cannot be over-stated. From simple maintenance  to high-end rebuild projects, this area of service is one of the most important revenue streams for your business today and tomorrow.

As we all know, the diversity and selection of engine oils available today can seem mind-boggling. We have choices of “conventional” oil (petroleum based), high-mileage oil, synthetic blends and full synthetics. Trying to make sense of it all, or should I say, advising customers with regard to selecting an oil, can sometimes seem frustrating.

As a default, you can always play it safe and stick with whatever type of oil (and viscosity range) that is recommended by the vehicle manufacturer.

“High mileage” engine oils are designed and marketed for use in engines that already have about 75,000 miles of use. This type of oil typically features formulations that offer increased detergent properties to minimize sludge accumulation and are mixed to reduce the potential for oil consumption.

Specific formulations are somewhat proprietary, so we generally don’t know what specific ingredients are used in the mix, but the point is that these oils are designed to help extend the life of a high-mileage engine.

Synthetic blends, sometimes referred to as hybrid oils, are comprised of traditional petroleum-based oils with synthetic additives to increase the lubricity and oil-cling properties, as well as providing quicker oil delivery during cold starts. The advantage of using a blend: you gain some of the benefits of a full synthetic at a lower cost. Full synthetics offer superior (I should say quicker) oil delivery, and are designed to transfer heat faster while providing a super-slick film to reduce friction. Again, the decision on which type of oil to use is often based on what the automaker recommends. One potential downside to using a full synthetic involves older engine designs where clearances and seal designs are not appropriate.

For instance, an older engine design that uses a two-piece rear main seal is likely not a good candidate for a full synthetic. Full synthetic oils, by and large, provide a greater propensity for external leakage. In short, if there’s a way to get out, a full synthetic will probably find it. The engine sealing design must be extremely efficient in order to handle a full synthetic. That’s why a full synthetic is not a good choice for vintage/collector cars such as those made in the 1960s and ’70s muscle car era. A quality full synthetic can do an outstanding job of lubricating, but it poses a greater potential for leakage.

Regardless of the specific type of oil selected, the subject of oil change intervals seems to be a constant topic of discussion. Again, following manufacturer recommendations is always the “safe” position. With that said, some automakers recommend extended intervals of perhaps 10,000 to 20,000 miles and possibly beyond. While these long-duration oil change recommendations may appeal to some customers from a budget standpoint, technicians often vary in their opinions.

If you can convince customers to have their engine oil and filter changed on a more regular basis, this can only benefit them in the long run. Some customers might rather spend a little more money by purchasing oil and filters on a more frequent basis simply in an effort to keep the engine clean, reducing the chances of sludge buildup and to keep oil passages clean and free-flowing.

Those who are more concerned with engine care may not mind spending a small amount of money more frequently in order to protect bearings and all frictional surfaces. Especially with a diesel engine, where contaminants are more easily deposited in the lubrication system, it may simply makes sense to “spend a little now to avoid spending a lot down the road.”

The trend for automakers to feature smaller displacement engines (in an effort to improve fuel economy) has led to the use of direct-injection (GDI: gasoline direct injection), higher compression ratios and the increased use of forced induction such as turbochargers in order to obtain desired performance. As a result of increased compression and turbocharger use, engine oils that are able to withstand higher operating temperatures in order to minimize coking and combustion chamber deposits and to maintain a constant and critical flow to turbochargers have been developed.

An example is GM’s recently specified dexos1. We’ll see more of these oil requirements mandated by automakers, so it’s more important than ever to be aware of an engine’s oil specification.

Oil filters

All engine oil filters are not created equal. The old adage “you get what you pay for” definitely applies. Bargain-basement filters may not provide efficient filtration, or may create a pressure issue. In the case of an engine that operates on a higher pressure (let’s say in the 50 psi or higher range), a cheap filter’s casing wall thickness may not provide enough strength to deal with this pressure, potentially resulting in a burst canister or a blow-out of the filter’s gasket. Do yourself and your customers a favor and stick with known-quality filters, and avoid no-name/inexpensive filters.

We shouldn’t have to remind anyone of this, but always follow basic filter installation guidelines. Make sure that the filter mounting base is clean and free of grit or other contaminants. Always apply a film of clean engine oil to the filter’s gasket, and always install the filter at the recommended torque value.

Realistically, it’s not practical to advise using a torque wrench, but a simple caution of proper tightening (avoiding under- or over-tightening) goes a long way to establish a secure attachment to avoid leaks such as those that can result from over-tightening and crushing the rubber gasket.

Also, as long as the filter location is such that it’s not upside-down or near 90 degrees, filling the filter with fresh oil prior to installing aids in more immediate oil flow. It’s not a deal-breaker, but when possible, pre-fill the filter.

Although shops other than racers rarely take the time to inspect a used filter, consider this. Using a dedicated oil filter cutter, the casing can be removed to expose the filter media, allowing you to inspect the filter material for signs of metallic deposits, which can be used as a diagnostic to help determine the condition of engine bearings. Granted, it’s an extra step that may take another 10 or 15 minutes, but it’s something to at least consider.

Also, never assume that you have the correct oil filter for a given application. I’ve encountered a few filters that were improperly packaged, with a filter that has the wrong thread size or incorrect gasket diameter. It’s not common, but take the time to check before attempting to install it.

Transmission oil and filters

One of the reasons that we need to change engine oil on a routine basis is because combustion heat and combustion by-products tend to contaminate the oil. Also, if the fuel system has been running rich and/or injectors have been dripping with the engine off, the oil becomes contaminated and thinned-out. If the engine’s coolant leaks into the oiling system (crack or pinhole in the block, damaged head gasket, etc.) this further contaminates the oil and lowers its lubrication properties. With that said, a transmission is not exposed to fuel, combustion deposit or coolant contamination. That’s why transmission fluid change intervals are much longer.

However, exposure to heat (thermal breakdown) is the enemy of transmissions and their lubricating oils. Because the tranny may seem to operate fine, and if they see no evidence of external leaks, far too many customers tend to completely ignore the need to replace this fluid. It’s your job to remind them, and urge them to have their transmission fluid (and filter, in the case of automatic models) changed per the automaker’s mileage recommendation. A fluid and filter change is a heck of a lot cheaper than replacing a transmission.

Cabin air filters

It’s easy to ignore a vehicle’s cabin air filter(s) — out of sight, out of mind. Let’s be honest: It’s easy to simply forget that they exist in the first place. However, starting with select models in the 1990s, cabin air filters have become commonplace, with over 80% of new cars fitted with these cockpit cleansers.

Replacing these filters benefits both the vehicle owner and the shop that is astute enough to highlight these filters on their standard lube and filter checklist.

According to MAHLE, cabin air filters are generally made of pleated paper or fleece and activated carbon. It sounds simple enough, but automakers and filter engineers have invested substantial R&D hours in order to determine materials, size, shape and location for these filters.

Granted, cars of yesterday weren’t equipped with passenger compartment air-filtering devices, and nobody griped. Back in the 1960s and ’70s, if someone said we needed to install an air intake system that would filter cabin air, he or she would have probably been laughed at and perhaps tarred and feathered. In today’s health-conscious society, you’d be ridiculed if you said there was no need for such a system. The world keeps changing and we simply need to adapt and keep up. Cabin filters are here and we need to deal with them.

Cabin air filters provide three key benefits:

  • They improve breathing safety by removing dust, pollen and other allergens.
  • In certain instances, they also help to remove unpleasant odors via the filter’s activated charcoal layer (at least helping to nix the stink of a skunk, the perfumed air of a farm’s fertilized fields or the petro smell from an over-fueling diesel).
  • Cabin air filters help to protect the vehicle’s HVAC system blower fan from ingesting damaging particles.

Note that once a vehicle has been outfitted with a cabin air filtration system, this creates an air path to the HVAC blower fan. If airflow through the filter is restricted, the blower motor is forced to work harder (similar to a clogged filter on your home furnace).

Generally speaking, cabin air filters should be replaced about every 15,000 to 30,000 miles. Vehicles operated in dusty environments should be treated to a fresh filter at least every 15,000 miles.

Air quality issues aside, be aware that humidity and storage times can easily contribute to filter issues. In damp conditions, especially for a vehicle that is stored for extended periods, the filter can easily become moldy, storing spores that are trying to work their way through the filter.

It should be obvious at this point that I recommend adding cabin air filters to your shop’s routine vehicle check, and for you to recommend a cabin air filter change at the same time as every engine’s air and/or oil filter change.

Simply make it a standard part of routine maintenance, instead of treating it like the “filter whose name must never be mentioned.” Let’s stop ignoring it and add it to the daily grind. The customer paid for this technology when he or she bought the vehicle. It just makes sense to maintain it.

Do your research and determine the location of cabin air filters for the vehicles your shop encounters. Depending on vehicle age and model, the filter will likely be accessed underhood, via a removable cowl panel on the passenger side; or via the glove box compartment (the glovebox tray may need to pivot down to gain access).

Stock cabin air filters for your most popular vehicles. Also, change your signage to include cabin air filters along with oil changes or other routine maintenance jobs.

Explain the benefits of the cabin filters to the customer. He or she may not even be aware that their vehicle is equipped with this system. Once they understand that the filters help to keep the cabin air clean and protects their blower fan from wear, selling replacement filters should be a piece of cake.   ■

See oil category charts by clicking here, pages 44 and 45.

Related Articles

Engine Oil and Cabin Air Filtration

Enemies of the Road: A Look at the Various Causes of Tire Damage

The Local Wrench: An Automotive Gem in the Picturesque Northwest

You must login or register in order to post a comment.