Frequently asked questions

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.

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.

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.

While most 15W-40 viscosity grades will satisfy the cold-weather startup temperature requirements in the U.S., 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. Advanced full synthetic Mobil Delvac 1™ engine oils are formulated to provide increased cold-weather startup protection even in severe weather conditions. Additional options that fleets or owner-operators should consider are synthetics like our Mobil Delvac™ Extreme engine oils.

Engines will experience the highest wear during cold startup, as lubrication to bearings and the upper-engine hardware is limited during startup and initial warmup. 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.