From the Magazine: Tips for choosing the right motor oil

From the Magazine: Tips for choosing the right motor oil

No longer is there an oil that matches the season.

“The classic distinction between a pure summer oil and a winter oil has long been passé,” said Oliver Kuhn, deputy head of the oil laboratory at Germany-based Liqui Moly. “The only thing that matters is the change interval. And that depends on mileage and time.”

The only time a specific oil should be used in the winter is if the vehicle is going into hibernation.

Furthermore, synthetic oil options should be first and foremost when speaking with customers. Today’s engines demand better performance; mineral oils simply don’t cut it anymore.

But not all synthetics are the same. There are two distinct differences. One is the so-called PAO oil, a classic synthetic oil that came on the market in the 1970s. Chemically pure and effective, it’s expensive to produce. The other is what’s called HC oil, for hydro-cracking, which describes how they’re produced.

“HC oils are more modern and came up in the 1990s,” Kuhn explained. “Today, they offer the best possible performance for all modern engines.”

When a customer is presented with options, they may choose an oil based on price. Ideally, if they’re someone who wants to take care of their vehicle, they’ll default to the most expensive one — you get what you pay for, right?

No, that’s not necessary. It’s more important to choose the right oil.

“Today, motor oil is like a liquid replacement part,” Kuhn explained. “Putting in the wrong oil is like fitting the wrong replacement part. This threatens dangers that go beyond a little oil sludge. There are actually oil-engine combinations that destroy the engine after just a few hundred kilometres.”

Indeed, going with the right fluid type or specification is essential, Sean Nguyen, lubricant scientist and technical specialist at Pennzoil, told CARS.

“Viscosity is important, but the most important aspect of spring maintenance is proper fluid type, proper fluid level and complete fluid checks,” he said. “This includes everything from coolants to washer fluids to power steering and transmission fluids. It is not just about changing oil, it is total lubrication and protection of the customer’s vehicle. This brings customers back and protects a shop from future liability claims.”

And each car manufacturer has their own preferences when it comes to motor oil.

“Because each car manufacturer follows a different technological approach, the required oil properties deviate from one another. Sometimes, numerous properties can be combined in a single oil, but sometimes not,” Kuhn said.

Nguyen agreed. Follow the owner’s manual, he stressed. And not just for motor oil — for any fluid going into your customer’s vehicle.

“For example, transmission fluids have multiple specifications, types and viscosities. They vary from a simple Type F to Dexron/Mercon to Nissan CVT to specific dealer-only fluids like MB236.17. A fluid that is labeled ‘transmission fluid’ does not mean that it will be serviceable in all transmissions,” he said. “The same would apply to power steering fluids, brake fluids, differentials and others. Every manufacturer has specific fluid specifications and requirements. As you can see, it’s important to be certain that the correct fluid is installed in a vehicle.”

That’s why there’s no one-size-fits-all option. “Anyone who says otherwise either doesn’t know what they are talking about or wants to take you for a ride,” Kuhn told CARS.

Importantly, shops shouldn’t want their customers to skimp on motor oil.

“Modern engine oil has a number of important tasks: Lubrication is only one of them,” Kuhn said. “Oil must loosen dirt and keep it in suspension. Oil must dissipate the heat in the engine. It must contribute to lower fuel consumption. Only an oil that meets the vehicle manufacturer’s specifications can do all this.”

Put the interests of the customer first, Nguyen urged. “There are many brands and types of motor oil out there that will meet the API specifications, and some are better than others,” he said. “It requires proper education and research to know what premium brands are available to service their customers at certain price points.”

The effects of cheap motor oil may not be felt immediately. When damage does occur, it could be catastrophic.

As Kuhn noted, lubrication is just one of the jobs of motor oil. It’s especially important in moving along other additives that are key to vehicle longevity. “With some very modern motor oils, the base oil is hardly more than just the carrier fluid for the additive packages,” he said.

There are more than 50 different motor oil specifications. OEMs set their own guidelines to match the performance requirements of their vehicles, often exceeding minimum industry standards.

“Engine designs can vary widely between manufacturers, which can impact the performance of the oil,” observed Karin Haumann, OEM technical manager with Shell Rotella. “For example, bulk oil temperatures can impact the rate of sludge formation or oil oxidation. Increased performance of engine oil characteristics can facilitate enhancements in engine design without the risk of overstressing the oil.

“Using a motor oil that meets the specification of the OEM will ensure that the oil meets the specific needs of your engine.”

It all may sound complicated, Kuhn acknowledged. “But actually the solution is clear and simple: The decisive factor is that the oil meets the specifications which the car manufacturer has set for that model,” he said.

This article originally appeared in the February issue of CARS.