Frequently asked questions

The Automotive Petroleum Institute (API) has established two diesel engine oil specifications – one with backward compatibility for older engine technology ("CK-4") and one for use with newer engine technology ("FA-4").

Mobil Delvac 1™ ESP engine oils meet or exceed the requirements of the API CK-4 specification and are backward compatible. These oils also meet or exceed original equipment manufacturer (OEM) requirements for Caterpillar, Cummins, Mack and others.

Mobil Delvac 1™ Advanced Fuel Economy engine oil meets or exceeds the requirements of the API FA-4 specification and is not backward compatible. This oil meets or exceeds OEM requirements for Cummins, Detroit and more. Mobil Delvac 1 Advanced Fuel Economy engine oil can only be used in engines approved by the original equipment manufacturer (OEM) for API FA-4 lubricants.

Yes, ExxonMobil stands behind its products. Whether it’s our Mobil Delvac 1 advanced full synthetic engine oils, Mobil Delvac engine oils or ancillary products, we demonstrate our commitment to quality by offering limited warranties. See the warranties.

The latest claims and approvals are available on our product data sheets (PDS).

For quick access, you can scan the QR Code on the product’s label, which will take you directly to the PDS. QR Codes are currently only available on Mobil Delvac 1™ ESP 5W-40 engine oil, but we are planning to expand this convenience to other products in the near future.

For information on where you can purchase Mobil Delvac or Mobil Delvac 1 products, visit our “Where to buy” page. You can find an authorized distributor or truck services near you.

Mobil Delvac 1 synthetic engine oils are fully compatible with their mineral oil counterparts. Mobil Delvac 1 products are recommended for year-round use and can provide improved efficiency and cost benefits.

Please consult your original equipment manufacturer (OEM) application and oil drain interval requirements to confirm you are selecting the correct Mobil Delvac 1 synthetic oil for your equipment.

Mobil Delvac 1™ Advanced Fuel Economy is our most advanced heavy-duty diesel engine oil. This oil meets or exceeds the API FA-4 specification and is designed for latest-generation trucks with friction-modified engine technology.

Mobil Delvac 1 Advanced Fuel Economy engine oil can only be used in engines approved by the original equipment manufacturer (OEM) for API FA-4 lubricants.

To find out if your company’s equipment is a good fit for this product and the potential fuel economy benefits it offers, please provide your information to the ExxonMobil Technical Help Desk by clicking the “Contact us” button on this page (select “Fleets” from the “Topic*” drop-down menu) and a sales representative will contact you.

*Results may vary based on vehicle/engine condition, driving and environmental conditions. Consult OEM or ExxonMobil before implementing extended ODIs.

†Compared to an SAE 15W-40 engine oil. Actual savings are dependent on vehicle/engine type, outside temperature, driving conditions and your current engine oil viscosity.

‡Relative to conventional 15W-40 engine oil, and within Mobil Delvac 1™ product range. Actual fuel economy improvement dependent on vehicle/engine type, outside temperature, driving conditions and the viscosity of current engine oil.

§As compared to a mineral 15W-40 engine oil. Fuel economy improvements are dependent on vehicle/equipment type, outside temperature, driving conditions and your current fluid viscosities.

We have upgraded the formulations of all our Mobil Delvac 1 engine oils to meet or exceed the API CK-4 and FA-4 specifications, thereby offering outstanding all-around performance.

*Results may vary based on vehicle/engine condition, driving and environmental conditions. Consult OEM or ExxonMobil before implementing extended ODIs.

†Compared to an SAE 15W-40 engine oil. Actual savings are dependent on vehicle/engine type, outside temperature, driving conditions and your current engine oil viscosity.

‡Relative to conventional 15W-40 engine oil, and within Mobil Delvac 1™ product range. Actual fuel economy improvement dependent on vehicle/engine type, outside temperature, driving conditions and the viscosity of current engine oil.

§As compared to a mineral 15W-40 engine oil. Fuel economy improvements are dependent on vehicle/equipment type, outside temperature, driving conditions and your current fluid viscosities.

Mobil Delvac 1™ Advanced Fuel Economy engine oil can only be used in engines approved by the original equipment manufacturer (OEM) for API FA-4 lubricants.

To find out if your company’s equipment is a good fit for this product and the potential fuel economy benefits it offers, please provide your information to the ExxonMobil Technical Help Desk by clicking the “Contact us” button on this page (select “Fleets” from the “Topic*” drop-down menu) and a sales representative will contact you.

ExxonMobil is proud to showcase our technology leadership by offering a full range of API FA-4 engine oils. We look forward to supporting your advanced lubrication needs.

While an oil’s viscosity is an important characteristic, it actually does not say anything about an oil’s quality; neither does the oil’s color. To be sure you’re buying a quality oil, look at the bottle and ask yourself a few questions: Is the product a reputable brand such as Mobil Delvac™? Do the industry and original equipment manufacturer specifications listed meet the needs of my equipment? Am I buying the oil from a reputable store or distributor? Is there a way to make sure I am buying an authentic product? If you can answer yes to all of these questions, you know you are buying a quality product.

Some people equate cheap oil with the inexpensive cost of operation. But this is a myth. The minute a piece of equipment is filled with an oil, the oil leaves its legacy behind. When comparing a premium product like Mobil Delvac™ to a cheap oil, the cheap oil could lead to higher wear rates and increased formation of deposit, varnish and sludge – all leading to high maintenance costs and reduced equipment life. So, while the cheap oil may cost less to buy, Mobil Delvac oil can cost less to own.

Mobil Delvac engine oils can help to extend the life of your engine. However, the actual life of an engine prior to overhaul depends on many variables: choice of oil, oil drain interval, maintenance practices, terrain traveled, driving habits, fuel quality, load carried and ambient temperature (to name just a few). But using Mobil Delvac oils will certainly help keep the engine life odds in your favor. ExxonMobil stands behind its products; see our Mobil Delvac limited warranties.

While choosing a high-performing product like Mobil Delvac is a great step toward long equipment life, there are other key considerations. To begin with, you need a proper viscosity grade. A full synthetic 0W-20 product may provide significant fuel economy improvement, but it would most likely not run so well in a heavy-duty diesel engine. For that, a 5W-30 synthetic product is needed to provide protection against wear and maintain oil pressure. On the other hand, use of a 25W-60 in a modern, low emissions engine could also lead to premature engine failure since it may be too thick to properly lubricate all components, even at normal operating temperature. A proper preventive maintenance program is also critical to ensuring extended equipment life; this not only means that appropriate inspections, check-ups and work are done but also that they are done at the right interval.

Proper choice of oil, both in the engine and driveline, can have a impact on fuel economy. Two things to consider: A multigrade product tends to provide better fuel economy than a monograde (e.g., a 15W-40 is better than a 40 grade) and lower viscosity products tend to provide better fuel economy than higher viscosity products (e.g., a 5W-30 provides better fuel economy than both a 10W-30 and a 15W-40). As equipment ages, deposits and wear accumulate, resulting in a decrease in equipment efficiency. Mobil Delvac™ lubricants help to protect the engine against deposit formation and wear, and resist soot-induced and oxidative viscosity thickening, allowing the equipment to maintain fuel economy throughout its life.

Some Mobil Delvac™ engine oils meet API and ACEA requirements for both gasoline as well as light-duty diesel engines, on top of its heavy-duty credentials, so be sure to check the oil’s performance claims versus your OEM requirements to ensure a match.. Mobil Delvac oils are formulated to protect a wide range of heavy diesel off-highway vehicles and equipment, including Class-8 big rigs, pickup trucks, diggers, excavators, dozers, graders, tractors, dump trucks and more.

Get all of the information you need by searching the SDS database or the PDS database. Safety Data Sheets (SDS), formerly known as Material Safety Data Sheets (MSDS), and Product Data Sheets (PDS) are important resources for manufacturers, fleets, fleet managers and owner/operators.

Mobil Delvac™ lubricants are formulated with a balanced additive system to provide outstanding performance for equipment. We invest millions of dollars testing our formulations to ensure this performance. Use of an aftermarket additive can easily throw this balance off, potentially causing severe problems. Additionally, many equipment builders now state in their service manuals that they specifically recommend against the use of these aftermarket additives. When you make a decision to purchase Mobil Delvac products, you can rest assured that they are formulated to provide optimal lubricating performance without any need for additional additives.

Regardless of whether you’re moving supplies in the frost of the Arctic, hauling trailers up and over mountains, or traveling in the heat of the desert, synthetic lubricants provide optimal protection in some of the harshest of driving conditions. Synthetic lubricants resist degradation at high temperatures better than conventional oils, leading to long oil life and reduced deposits, sludge, and varnish formation. At low temperatures, synthetic lubricants flow better than conventional oils, allowing them to reach components faster in order to provide quicker and better protection against wear. Because synthetic lubricants impart lower friction properties under load, they can help equipment operate more efficiently than conventional oils. This increased operational efficiency can be seen in improved fuel economy and lower operating temperatures, particularly in axle and transmission applications. In addition, many equipment builders endorse extended oil drain intervals when properly approved synthetic oils are used. In fact, many of world’s transmission and axle builders provide an extended warranty for those using approved synthetic lubricants in their equipment.

Mobil Delvac 1™ synthetic lubricants are fully compatible with their mineral oil counterparts, and it is practical to switch. The outstanding performance improvements of Mobil Delvac 1 synthetic products over mineral oils can be realized at all kinds of ambient temperatures. To realize these benefits, including improved efficiency and cost benefits, Mobil Delvac 1 products are recommended to use all year round.