Light-duty vehicle drivers’ FAQs

It’s the job of engine and gear oils to reduce friction between moving parts, protect against corrosion and keep components clean. By coming between and adhering to metal, the lubricants ensure the components effectively 'float' on a thin film of oil, preventing the metal-to-metal contact that causes friction, heat and wear. By preventing the build-up of dirt, and keeping engine parts clean and in good condition, lubricants can also help prevent corrosion and premature engine damage. The better the quality of the oil, the better its long-term ability to perform these functions, ultimately increasing the reliability and performance of the engine. 
Base oils, viscosity modifiers and performance additives are the three vital ingredients that go into engine oils. Careful selection and skillful blending goes into formulating each lubricant to provide maximum engine protection.
As temperatures drop, the same cold temperature viscosity phenomenon occurs with drivetrain lubricants as it does with engine oils. Following the engine warm- up procedures mentioned above will also allow for sufficient oil circulation to your drivetrain components. For general-service transmissions used in on- highway Class 8 vehicles where ambient temperatures of -26°C or below exist, a heat exchanger is recommended to make warm-up times faster. Fully synthetic SAE 50 transmission and SAE 75W-90 gear oil lubricants, such as Mobil Delvac 1 Synthetic Transmission Fluid 50, will provide better low-temperature fluidity than conventional oils, as well as help reduce wear, leading to longer equipment life and allowing for easier gear shifting while operating cold.
Yes, you can change to a different viscosity according to vehicle usage, environmental and climatic conditions.
Yes. Mobil Delvac™ engine oils meet API and ACEA requirements for light-duty diesel engines, on top of its heavy-duty credentials.
It’s true that Mobil Delvac™ can help to extend the life of your vehicle engine. However, the actual life of an engine prior to overhaul depends on many variables from oil-drain intervals and maintenance practices to your driving habits and the load carried. But using Mobil Delvac engine oils will certainly help keep the engine-life odds in your favor.
Both in the engine and driveline, it can. So you have two things to consider: A multigrade product tends to provide better fuel economy than a monograde (e.g., a 5W-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 are able 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.
During winter weather conditions, vehicle suspension components can be subjected to more adverse conditions, such as increased water and contamination from road salting. Careful attention is needed to ensure that the suspension components are greased at a regular interval and the proper amount of grease is applied to help minimize the entry of road contaminants, and to replace grease that has been washed out due to excessive water exposure. It is also important not to over grease components as this can rupture seals and lead to reduced component life. A ruptured seal can lead to loss of grease and lack of lubrication as well as intrusion of road contaminants, water, dirt, etc. 

Differentials and wheel hubs can be exposed to increased water intrusion during winter months from wet road conditions, high water at curbs, road flooding, etc. The lubricant condition should be inspected for water contamination when levels are checked. A visual inspection that shows a hazy or cloudy appearance or visible water droplets can indicate an excessively wet lubricant. Any indication of water intrusion should be investigated for the cause and the lubricant changed.
While most 15W-40 viscosity grades will satisfy the cold-weather startup temperature requirements in the United States, engine oil specifications should be referenced to ensure that properties such as pour point, cold cranking viscosity and cold-temperature pumping viscosity meet an engine's coldest operating temperature requirements.

Premium engine oils such as Mobil Delvac 1™ LE 5W-30 are formulated to provide increased cold-weather startup protection at temperatures as low as -26°C. Additional options that fleets or owner/operators should consider are using a fully synthetic like our Mobil Delvac™ XHP ESP, or our flagship Mobil Delvac 1 ESP series, which is formulated to deliver exceptional protection even in severe cold weather conditions.

Engines will experience the highest wear during cold startup, as lubrication to bearings and the upper-engine hardware is limited during startup and initial warm-up. The engine oil's viscosity at starting temperature is an important factor in determining whether or not an engine will start.

Using too heavy a viscosity during cold temperatures can result in inadequate lubrication during startup. If the chosen lubricant has a viscosity that is too high, the oil filter bypass valve – assuming the truck has one – will open and allow unfiltered oil to bypass the oil filter (the bypass valve maintains the lubricating oil flow to the engine and prevents an oil filter collapse). The bypass valve will close as the engine oil warms up and thins out. It is equally important to adequately warm up an engine before loading it. The best practice is to idle for a short period and warm up the engine by operating at a low rpm and load condition.
Many truck engines idle for very prolonged periods during cold winter temperature conditions to allow for warm-up and to keep the cab warm.

Prolonged idling will reduce engine life and also waste fuel. Engines operate cooler while idling, and during long idle periods in winter's cold temperatures, moisture in the intake air can condense in the engine crankcase and produce corrosive sulfuric acid, which can attack soft bearing alloys. Long idling also contributes to increased soot and combustion contaminants, which will shorten the engine oil's life prematurely and can lead to excessive piston deposits, sludge formation and detrimental viscosity effects.
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.
No. Look instead for a reputable brand like Mobil Delvac, for a product that meets specifications set by industry and original equipment manufacturers, and buy products you know to be authentic from a trusted supplier.
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.
Because they flow better at low temperatures, it’s possible to manufacture thinner synthetic oils and it’s these low viscosity oils that modern engines need to help reduce fuel consumption and emissions. Synthetic oils also have a higher film strength, which gives better protection and reduced wear. And, as they are more stable and less volatile at high temperatures, they work better for longer, effectively reducing the engine’s oil consumption.
Viscosity is a measure of thickness. At low and high temperatures, the viscosity of oil is measured on a scale determined by the Society of Automotive Engineers and given an SAE number to indicate this – so an SAE 30 will be thinner than an SAE 40 oil. 
During the winter, all vehicle lubricants – whether engine oil, transmission oil, differential oil, hydraulic oil or grease – should be considered. Before starting equipment in extremely cold temperatures, an operator should make sure the oils in the engine, transmission and hydraulic system are fluid enough to flow. Check the engine oils using the dipstick where applicable; other fluids should also be checked by their appropriate methods.
Mineral oils are derived directly from the crude oil refining process, whereas synthetic oils are altered by chemical processing which improves their chemical structure. As a result, synthetic oils perform better than mineral oils at all temperatures, and are more durable. As they are higher quality, offer higher performance and longer life, fully synthetic oils cost more than mineral oils.
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.
Changing oil performance standards are directly related to continuously evolving emissions and fuel economy regulations. In an effort to obtain cleaner air, the trucking industry must abide by these governmental regulations. That means they are constantly making design changes to their equipment, generally resulting in a harsher environment for the oil: higher temperatures, higher soot loads or even the need to be compatible with after-treatment systems. Bottom line? Low emission engines need higher performing products. Therefore, when emissions regulations change, so do oil specifications. Even if you have an older engine that does not meet the latest emissions standards, it still benefits from oils that are formulated to the latest standards.