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 For the 2011 model year, GM will introduce dexos1™ certified engine oil as a factory fill and service fill for many engines. The reason for the new engine oil specification is three-fold: meet environmental goals such as increasing fuel efficiency and reducing engine emissions, promote long engine life, and minimize the number of oil changes to help meet the goal of lowering the industry’s overall dependence on crude oil. GM as well of other manufactures like Mercedes Benz, BMW, Audi, Volkswagen have also created vehicle specific oil blend specifications.

dexos is a GM-developed engine oil specification that has been designed to:

Improve Fuel Economy

New technology being introduced in GM vehicles designed to address vehicle efficiency and fuel economy include direct injection, cam phasing, turbo-charging and Active Fuel Management. The demands of these technologies on engine oil also are taken into consideration when determining new oil specifications. Active Fuel Management, for example, can help to achieve improved fuel economy, however, alternately starting and stopping cylinders puts a lot of stress on engine oil.

Another industry trend for meeting tough fuel economy mandates has been a shift toward lower viscosity oils. Testing has shown that thinner 0W-20 oil can provide as much as a 4% improvement in fuel economy than 15W-40 oil. .

Emission System Operation

Oil contains Phosphorous, an additive for wear, corrosion and oxidation it’s critical that it needs to be retained within the oil to prevent poisoning of the catalytic converter, and air fuel sensors. As well as the oil must contains additives for keeping internal engine parts clean. Deposits are not beneficial to fuel economy, wear issues, timing knock concerns and compression concerns. Additives must clean enough to prevent deposits but not too much to clean away the additives that help protect against metal friction wear.

Engine Sealing Materials

Compatibility of the oil with sealing materials is critical not only for the consumer but for the manufactures as reducing potential oil leaks is a costly concern.

 Engine Sludge Protection

Most manufactures are now providing longer warranties on the engine assembly, thus the need for oils that prevent sludging and deposits are required. With longer oil drain intervals being introduced dispersants are used to control sludge effects and lubrication.

 E85 Rust Protection and Emulsion Retention

An increasing number of vehicles are now flex fuel compatible, able to run on ethanol. GF-5 oil must be able to protect against rust and corrosion that environmentally friendly ethanol causes when it is burned. The by products of E85 are water and acids that end up in the engine oil.

 Oil Life Monitor Systems

Some oils are designed and formulated to meet the monitoring conditions of the Oil Life Monitor system. Usage of other oils may prevent the accuracy of the management system thus triggering the light on too late or too early. A cost increase will most likely be seen with the usage of these oil as much as 20-30% more.  However with the operation of the oil life management system and proper vehicle maintenance GM estimates that more than 100 million gallons of oil could be saved annually.

TIP: The oil level and quality should be inspected regularly, as we have seen vehicles with higher mileage 150,000kms plus begin to exhibit mechanical failure due to increased drain intervals with incorrect oils, or operating an engine with worn, sludgy oil.

 Industry Standardization

Ensure worldwide availability of high quality oil for factory and service fill needs. Prevent the concerns with non OEM approved oils from being used in a GM vehicle. Many oil manufactures are ensuring they are compatible with the GM dexos1 and dexo2 standards. However there are some concerns about trade licensing fees and requirements.

TIP: The oil specified in prior model years remains acceptable for previous models; however, dexos1 is backward compatible for older vehicles.

TIP: Using the right viscosity grade oil is critical for proper engine performance. Always check the appropriate vehicle owner manual for the proper viscosity grade for the vehicle being serviced.

Carlo Sabucco

Sils Complete Auto Care Centre ( Using the right oils – every time )

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