Extend Oil Life

John Baxter | April 01, 2012

With smart operation, you can save money by providing a greater cushion against lube deterioration and engine wear.


Oil might cost more than you realize, especially if you’re not getting maximum use of it. Do a typical change yourself and it still costs about $250 for the oil alone.

Carry extra oil with you, pull the stick daily and keep the crankcase filled to the top. The full volume of oil increases available additives and eases the work done by each quart of oil, thus helping extend the life of an oil change.

But assume you extend your change interval from 15,000 miles to 25,000 miles. That extension over the million miles of an engine’s expected lifetime would save a lot. Allowing a modest amount for disposal costs and nothing for downtime or labor, the total savings from adding 10,000 miles to change intervals over 1 million miles would amount to about $7,800.

The typical conservative interval for many owner-operators, 15,000 miles, has been shorter than the standard recommended over-the-road change interval for most engines since the early 1990s. Operators adhere to 15,000 miles because they have heard of many oil-related engine failures at changes longer than that conservative interval.

But oil life is quite flexible. A competent operator can extend that life significantly by paying attention to his maintenance and altering his operation behavior. For example, experts agree that minimizing idling time alone will significantly extend oil life because idling puts more undesirable stuff in the oil than even hard driving. Responsible refiners are willing to stand behind their products even when extending changes. Operating and maintaining your vehicle or vehicles as the experts advise could allow you to extend changes without fear of problems. It could also reduce costs and give you more downtime.

Chevron Lubricants’ Jim Gambill, Delo’s brand manager for the Americas, says the “real issue with extending drains is the maintenance of the vehicle – fuel filters, tires, oil, grease, coolants, etc.”

The critical practices are those that affect the stress on oil. Oil lubricates wear surfaces, but it also cools such critical parts as the pistons, which are not in direct contact with the radiator coolant. When those high temperatures are combined with the oxygen in crankcase air, as well as in the cylinder (for oil sitting on the liner during a down-stroke of the piston), the result is thermal and oxidation-related breakdown. That can quickly destroy oil’s ability to lubricate.

The engine’s primary defense against this heat is the cooling system – especially the oil cooler’s, consisting of copper pipes with coolant on one side and oil on the other that conduct heat into the coolant. Should even a thin layer of scale coat those pipes, oil temperature would rise. The oil cooler can bring temperatures down from about 300 degrees to close to 200 before releasing it into the pan. Without it, oil would decompose quickly during sustained engine operation.

“It’s all about maintaining the optimum operating temperature, which will reduce the thermal stresses and oxidation rate of the oil,” says Rob Banas, commercial vehicle lubricants application engineer with ExxonMobil.

“If the engine temperature is higher, the oil degradation rate will be higher,” says Dan Arcy, Shell Lubricants OEM technical manager. “Glance at the oil temperature gauge every now and then.” Arcy also suggests keeping an eye on the coolant temperature gauge and performing maintenance such as flushing out bugs and debris that have clogged radiator fins to keep engine temperature at the optimum level.

“Other areas of oil stress include allowing impurities such as antifreeze, fuel, or dust in. If you find your coolant level is changing, this should be a red flag” for system problems, says Gambill. An external leak is less problematic than an internal one, where coolant will mix with the oil, react chemically and interfere with the oil’s performance.

Maintaining coolant level maximizes the performance of the radiator by increasing the surface available for heat to be transferred to outside air, Gambill says. You need to keep the system full and properly protected from corrosion by using ELC or with Supplemental Coolant Additives to prevent scale that traps heat.

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