Know Your Motor Oil: GM’s New dexos

If you drive a 2011 General Motors vehicle (and if you buy a GM vehicle in coming years), there is or will be a new motor oil in your car or truck. 

In October of this year, General Motors began licensing motor oil that meets a new proprietary (i.e. GM-only) specification, trademarking that specification/license as “dexos” (the lowercase is, oddly enough, correct).

So what does that mean for you, the driver? “First of all, dexos is a motor oil specification, not a recipe,” noted Eric Johnson, senior project engineer with GM Powertrain-North America’s Fuels & Lubricants division. “It’s the first common engine oil specification General Motors has ever developed that will encompass all our companies in all our markets.”

While the specification might not be a recipe, it is stringent enough that virtually all motor oil blenders have responded by creating dexos-spec products that are made of synthetic motor oil. That’s right. When it comes time to change your oil, you’ll need to use a synthetic motor oil.

That means, for starters, that your oil changes will likely be more expensive than in the past. But it also means you’ll be getting the ultimate in protection, a motor oil that can last the duration of the extended oil change intervals recommended by your Engine Oil Life System (EOLS), the little reminder in your car that tells you when it’s time to change the oil.

The dexos specification was first conceived in 2006 and developed in 2007. Motor oil blenders were apprised of the specifics in 2008 and 2009, and informed that in order to meet factory warranty requirements, products meeting the dexos spec would need to be licensed by GM beginning this year. (There are actually two dexos specifications: dexos-1 for gasoline engines and dexos-2 for diesel engines. For 2011 vehicles, only dexos-1 is being installed at the factory.)

According to Johnson, GM had several goals in developing the specification. In addition to creating a common specification that would work across all brands in all markets, GM also wanted a product with improved fuel economy and fuel economy retention when compared with existing products. The dexos spec was also designed so the motor oil can function as a hydraulic fluid, an increasingly common design element in GM engines that use variable valve timing. And, the company hopes to further “optimize” drain intervals by increasing motor oil robustness through the dexos spec.

“When used with the EOLS, we will be able to increase drain intervals and reduce the amount of oil used during the lifetime of a vehicle,” Johnson said. “The EOLS will take into account the better quality of dexos products.”

So, the long and short of it is your new GM vehicle will, for warranty purposes, require a new, high-tech synthetic motor oil that will protect your new baby better than ever before. Plus, you’ll likely be able to drive it even further between routine oil changes if you follow the EOLS. True, you might have to pay a little more for your oil change, but in the long run that sounds like a fair trade to us.