2005 Buick Rainier Owner's Manual - Page 351

How to Check Lubricant What to Use To determine what kind of lubricant to use, see Recommended Fluids and Lubricants on page 6-12. Front Axle When to Check Lubricant It is not necessary to regularly check front axle fluid unless you suspect there is a leak or you hear an unusual noise. A fluid loss could indicate a problem. Have it inspected and repaired. To get an accurate reading, the vehicle should be on a level surface. The proper level is from 0 to 3/8 inch (0 to 10 mm) below the bottom of the filler plug hole. 5-47