Sometimes, the answer to a question about motor oil can be found as easily as by opening a book. Specifically, the vehicle’s owner’s manual.
Whether it’s a customer walking through the doors or a service and repair shop on the other end of the phone, these days, that’s perhaps the best way to make sure a jobber is selling the right motor oil.
“It will include information on service intervals, fluid type guidelines and specifications and fluid volume needs,” explained Sean Nguyen, lubricant scientist and technical specialist with Pennzoil. “It is crucial that the manufacturer-recommended and -approved fluid be used for the specific vehicle in question.”
There’s motor oil for low-mileage vehicles; some may require a specific viscosity; some manufacturers may make requirements based on vehicle performance. And those are just a few examples.
Indeed, just like other fluids, motor oil requires careful consideration.
“A fluid that is labelled ‘transmission fluid’ does not mean that it will be serviceable in all transmissions,” Nguyen 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.”
And it’s not necessarily about picking the most expensive motor oil either.
“It is not about which oil is supposedly better,” said Oliver Kuhn, deputy head of the oil laboratory at Liqui Moly. “The decisive factor is that the oil meets the specifications which the car manufacturer has set for that model.”
Again, he pointed to the owner’s manual as the primary source for getting the right information. That said, companies like Liqui Moly offer training to get the right information out there.
“We support with training so that the knowledge in the shops is always up to date as much as possible,” he told Jobber News. “A reliable and quick help is our free Oil Guide. It is aimed at everyone — laymen and professionals.”
“It is not about which oil is supposedly better. The decisive factor is that the oil meets the specifications which the car manufacturer has set for that model.”
There is no way around the approvals and recommendations for motor oil, Kuhn added. “These are the authoritative guide values. It is essential to comply with them.”
Still, we asked the pros to help pass on some knowledge. For Nguyen, he highlighted key differences in motor oil, such as viscosity, additives and so on.
“The motor oil viscosity recommended by the equipment manufacturer is chosen to best fit a particular engine design and need,” he told Jobber News. “Using the proper viscosity will help to protect and extend the life of a vehicle’s engine. Every oil manufacturer will have their own specific motor oil formulation based on specification needs and performance.”
There has been some discussion as to whether low-viscosity motor oils are fine to use in warm weather. Pennzoil’s research — which included using SAE 0W-20 for engines calling for SAE 5W-20 as well as testing with New York and Las Vegas taxi fleets — reported no issues.
“We saw no issues associated with lower viscosity use, and actually recommend using the lower viscosity oil all year round as long as the operating SAE viscosity is correct (XW-20),” Nguyen said. “In fact, using a lower-viscosity oil has been shown to help with fuel economy while still giving the protection needed at operating temperature.”
For Kuhn, seasons don’t play a role in determining the right motor oil to use.
“Only in the case of vehicles that are immobilized in winter, it is an important aspect,” he said, adding that cars or motorcycles that only operate from spring to fall should get an oil change as owners prepare to put the vehicle in hibernation.
“The classic distinction between a pure summer oil and a winter oil has long been passé. The only thing that matters is the change interval. And that depends on mileage and time.”
“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.”
But viscosity isn’t the only important consideration, Nguyen pointed out. Pay attention to fuel type and specification that’s recommended by the vehicle manufacturer. Furthermore, ensure the customer’s fluids are at proper levels and complete checks are being done.
“This includes everything from coolants to washer fluids to power steering and transmission fluids,” he explained. “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 not all synthetics are the same. There are two ways synthetics are produced. One is the so-called PAO oil, a classic synthetic oil that came on the market in the 1970s. It is chemically pure, making it effective. But it’s also very expensive to produce.
The other method is hydro-cracking, giving the technical jargon name of ‘HC oils. More modern, these came up in the 1990s. Kuhn said these offer the best possible performance for all modern engines.
Liqui Moly’s specialty lies in European vehicles. Kuhn observed that each manufacturer’s specificity means there often can’t be a one-size-fits-all 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,” he said. “This means that the general lubricant from previous decades has become a highly specialized liquid. And that’s why there cannot be a universal oil today that fits all vehicles. Anyone who says otherwise either doesn’t know what they are talking about or wants to take you for a ride.”
What happens if a customer uses the wrong oil?
“Using improper fluid can lead to fluid incompatibility and potential equipment damage, which could result in vehicle breakdown and expensive repairs,” Nguyen said.
This article originally appeared in the March issue of Jobber News
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