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High Mileage Motor Oil - Is It Worth It?


High Mileage motor oils have been marketed in the US since the late 1990’s. This segment has grown significantly since its introduction in alignment with the increased age of the vehicle population which is an average of approximately 12 years. In fact, most of the vehicles on the road today actually fit the high mileage profile.


The commonly adopted industry definition of “high mileage” is an engine that has more than 75,000 miles on the odometer. A high mileage motor oil provides benefits focused specifically on conditions that an aging engine can experience. These specialized lubricants contain customized additives designed to take care of aging engines while also being completely suitable for newer engines as they meet all of the latest industry standards. These products deliver improved oil burn- off performance which can provide additional protection in an engine where oil consumption has increased over time. High Mileage oils will also contain higher levels of detergents and seal conditioners to help to protect aging seals and gaskets from becoming brittle which will help prevent against leaks providing enhanced protection for the specialized needs of older engines


Should I use high mileage oil or full synthetic oil?

While we always recommend following your manufacturers recommendation for viscosity grade and performance specification, it’s important to note that manufacturers will never call out “high mileage” within their oil recommendation.  This is simply because their recommendations are issued when the vehicle is new and not updated as the engines ages. 


A full synthetic oil that meets the manufacturer specification requirements can always be used in a high mileage vehicle.  Full synthetics generally will offer excellent oil burn off protection, higher levels of heat resistance and thermal stability, enhanced deposit control protection and excellent anti-wear performance. The best of both worlds would be to select a full synthetic high mileage oil to carry the performance advantages of both a full synthetic and the added features of a high mileage formulation.

How long does high mileage oil last?

Some consumers believe that the term “high mileage” refers to longer spans between oil changes also known as extended drain intervals.  This a common misconception and is not correct.  Instead, it refers to the benefits associated with the lubricant designed specifically to meet the needs of an aging engine.  The recommended oil drain interval for your vehicle can be found in your owner’s manual or via our CASTROL® OIL FINDER which can be accessed here.

What is unique about castrol high mileage oil ?

Castrol offers the choice of two High Mileage motor oils, Castrol GTX High Mileage which is the #1 high mileage oil among “do it yourself” consumers and Castrol EDGE High Mileage, an advanced full synthetic formula that extends maximum performance.  Both high mileage motor oils are formulated to reduce burn off and include seal conditioners to protect against leaks.

But it’s Castrol’s phosphorus reduction technology that provides a unique benefit. 

One of the key issues that older vehicles often encounter is failure of the catalytic converter, a critical part of the vehicle’s emission system. If it requires replacement, the cost can exceed the value of the vehicle so protecting the emission system can ultimately extend the life of your car.  Both Castrol High Mileage engine oils are blended with a patented additive that reduces the amount of phosphorus, a known poison to the catalytic converter, in the formulation. By lowering the level of phosphorus, Castrol High Mileage oil products help prevent emission system failure and extend the life of your high mileage vehicle.

CASTROL EDGE HIGH MILEAGE – premium protection and performance

Castrol EDGE High Mileage is an advanced full synthetic motor oil with the high-level protection of GTX High Mileage and then adds the benefits of full synthetic technology delivering higher levels of thermal stability, deposit control and excellent anti-wear performance. In addition, Castrol EDGE High Mileage, in the 0W-20, 5W-20 and 5W-30 grade, is approved by General Motors for dexos® 1 Gen 2 applications.