How to Choose the Oil and Fluids for a GMC Sierraby Contributor
The GMC Sierra, introduced in 1999, is essentially the same vehicle as the Chevy Silverado and the Mexico-only Chevy Cheyenne. As such, maintenance requirements are essentially the same. These steps apply to all GMC Sierra model years, although vehicles that have been heavily modified for specialty uses like off-road racing may have unique maintenance requirements.
Use Delco Supreme 11 brake fluid or a DOT-3 equivalent to maintain your stopping power. If you're using your vehicle for off-road racing or other high-impact uses that may require a lot of braking, consider using a specialty brake fluid to prevent boil over.
Maintain your 5-speed transmission's hydraulic clutch system with hydraulic clutch fluid, GM part number 12345347 in the U.S. and 10953517 in Canada, or use a DOT-3 equivalent brake fluid. The 6-speed transmission requires a different clutch fluid, GM part number 88958860 in the U.S. and 88901244 in Canada, or a Super DOT-4 equivalent.
Refill your power steering fluid reservoir with GM power steering fluid, U.S. part number 89021184 or Canada part number 89021186.
Change your DEXRON-III automatic transmission fluid regularly if you have an automatic transmission. You can also use this transmission fluid in the GMC Sierra manual transfer case. If you're running a manual transmission, see Tips below for information about manual transmission fluid.
Lube your rear axle with an SAE 75W-90 synthetic axle grease. If you have a steerable rear axle, it's vital that you don't add a friction modifier. For the front axle, use an SAE 80W-90 axle lubricant.
- Because a variety of manual transmissions were produced in this vehicle, one of several transmission fluids may be required. For a 5-speed manual transmission with low gear, RPO MW3, use GM Goodwrench synthetic manual transmission fluid or an equivalent SAE 75W-85 GL-4 gear oil. The 5-speed manual without low gear, RPO MG5, requires Synchromesh transmission fluid, GM part number 12345349 in the U.S. or 10953465 in Canada. A 6-speed manual transmission requires a synthetic transmission fluid approved to "Allison Transmission" specification TES-295. This is GM part number 12378515 in the U.S. or 88900701 in Canada.