A GMC Envoy needs an SAE 5W-30 oil. You can use synthetic but any motor oil of this weight would be fine.
Motor oils use a rating system developed by SAE, which is the Society of Automotive Engineers, to classify oil by viscosity.
We’re all used to seeing designations like SAE 5W-30 or SAE 10W-30. Here's a brief explanation of what they refer to:
For multi-grade viscosity oils, the cold-temperature viscosity is labeled with a “W,” which stands for “winter.” Thus, in an SAE 10W-30 oil, the “10” is the cold-temperature viscosity rating, and the “30” is the high-temperature viscosity rating.
This combination provides an oil that flows well at low temperatures, but still protects the engine at high temperatures.
For comparison’s sake, SAE 5W-30 and SAE 0W-30 will flow better at even lower temperatures than 10W-30 while still providing protection at high temperatures. Just remember, the “W” stands for winter.
Refer to Pennzoil.com's Types of Motor Oil to learn more.
Engine oil is one of the most complex, extensively tested and continuously improved components for your car. But it's also among the least understood. Here's the information to help you make the best choice, shared by the experts at Edmunds.com.