Act now to avoid these lube, coolant and grease mistakes

It’s always a good idea to follow best practices in any maintenance program. But what about avoiding worst practices?

Here are some common mistakes construction equipment fleet managers make regarding lubes, coolants and greases.


Coolants can be the most commonly mishandled part of a fluid management program, since experts say they are the least understood. Unfortunately this lack of understanding can have catastrophic impacts and cost a lot of money.

All coolants are not alike nor interchangeable. There are two distinctly different types of coolant – older conventional fully formulated and the newer extended life (or organic acid technology or OAT). These two coolants protect engines from corrosion in different ways, and anytime you mix the two, you dilute or reduce their effectiveness.

The problem arises when someone tops off a radiator with the wrong fluid. Maybe the maintenance manager uses the right coolant. But does the operator, the field service guy, a contracted service provider, a driver or whoever first notices the low coolant level know this?

The different additives in those different coolant chemistries don’t help each other out. In mixing the two, you are setting yourself up for possible catastrophic corrosion – such as corrosion that eats a hole from the coolant side of a cylinder liner to the oil side. And by the time you see coolant show up in your oil samples, it’s too late. The major damage has been done.

Preventing and solving coolant problems

The solution is to make sure everybody – mechanics, operators, drivers, contract maintenance people – understands the brand and type of coolant used and the dangers of mixing two formulas. This requires training and perhaps an operator care program, and it should be your first line of defense.

The second line of defense is to monitor coolants with test strips made for your coolant type. Wet these simple paper strips with coolant in the system. If they turn one color, you’re good to go. A different color means your coolant doesn’t have a high enough percentage of the right additives to prevent corrosion.

Another recommended step is to check the freeze point of the coolant with a hygrometer, or for more accurate results, a refractometer. This will tell you if your coolant is too diluted with water, which also reduces its anti-corrosion properties.

If the coolant is out of spec, it’s not usually necessary to drain and refill the entire system, which on some machines can require dozens of gallons. Coolant vendors offer concentrated coolants to allow customers to bring the coolant levels to the recommended freeze points. A freeze point correction chart will show you how to adjust your coolant so that it is at the proper level. Correction fluids are used to restore additive content to recommended levels. These two procedures enable you to bring your equipment’s coolant back into spec without draining the cooling system.

Your coolant vendor can help you establish these procedures. A good practice is to check the coolant every time you change the oil.

Oil contamination

This is just basic housekeeping, but too often overlooked. Oil contamination can be a huge problem and ongoing challenge.

The problem can start with the oil delivered in drums or bulk containers. Contractors may be tempted to let drums sit outside in the rain because they think they are sealed tight. But the everyday heating and cooling cycle causes drums to suck moisture right past the gaskets on the bungs. A desiccant breather on your bulk lube oil tanks will go a long way toward preventing moisture contamination.

Moving oil from bulk storage to the machine also introduces opportunities for contamination. Some shops use dirty, open-top containers. And sometimes technicians will use a spare container previously used to handle other products such as coolant, transmission or hydraulic fluid. Even small amounts of these other fluids will compromise the effectiveness of your lube oil and cause erroneous readings in a used-oil analysis report.

Keeping lubricants clean, cool and dry will lead to better life for both the lubricants and your equipment. And keeping your lubricants cool means making sure your engines don’t exceed the recommended operating temperatures. As a basic rule, as the lube oil temperature increases, the oxidative life of the oil decreases.

Lube oil oxidation today is a big deal for engine oils in the heavy equipment world. Engines are running hotter, which is one of the reasons the oil industry developed a new lube oil standard, API CK-4, which requires heavy-duty diesel engine oils to better resist oxidative degradation.

Getting grease right

While greasing a machine isn’t the most technical task, doing it at the right intervals and using the right product are important. More often than not, putting less grease in more frequently is better than putting more grease in less frequently.

When you pump a lot of grease through a joint, most of it is wasted. The amount of grease that is doing the lubrication is actually very small, say lubrication experts. Sometimes it is no more than the size of a pea. The mechanical motion of the joint tends to squeeze that grease out over time. Until it gets regreased, it’s going to have no lubricant in the joint. So overextending grease intervals is not a good idea.

This is why central grease systems work so well. They give a tiny bit of grease frequently. Grease can also get contaminated, and by greasing more frequently, you purge the contaminated grease.

Moly greases — those that contain a small amount of molybdenum — are better at sticking in a joint. They stay put longer, but after a period of time, it also goes away.

Stick to your OEM’s specifications for all greasing applications. For example, a heavy-duty grease with tackifiers works better on joints under a heavy load. But those greases aren’t good for things like lubricating U-joints on drive shafts, with their small needle bearings and passageways.

Move from reactive to proactive

These days it seems everybody is trying to do more with less. In used-oil analysis, this may mean you’re not taking time to look at the results and understand the information these reports provide.

When fleet managers see a red flag on an oil analysis report, they have to pull the machine from the field and find out what’s going on. But such regressive or reactive maintenance is expensive in terms of downtime and damage to a machine.

Instead, pay attention to the trend line. Most of the time when a sample throws a red flag, a previous sample has given a hint that something is going wrong. Paying attention to those hints gives you a chance to be proactive and schedule workarounds to fix problems before they disrupt operations or become catastrophic failures.

The next step up is getting to the point where your ability to read and interpret a used-oil analysis becomes as much an art as a science. Several factors have an impact, including the environment, the application, the metallurgy of the equipment, the product and the severity of the application. But the effort has a great payback.

The end goal is to move toward a world-class maintenance program and key to that is institutional learning.

Do that, and the benefits and savings can be astronomical.