Transmission Fluid for a 2000 Chevy Silverado: What to Use
The Short Answer
Most 2000 Chevrolet Silverado trucks have a four-speed automatic transmission. These automatics were originally specified for Dexron III automatic transmission fluid (ATF). GM has since retired the Dexron III specification and replaced it with Dexron VI, which GM states is backward compatible. In practice, a fully licensed Dexron VI fluid is the current choice for a 2000 Silverado automatic.
Two qualifications change this answer. First, it applies only to automatic transmissions. Manual-transmission trucks use a different fluid. Second, the 2000 model year included more than one Silverado body style and more than one automatic transmission. You should identify which truck and gearbox you have before buying fluid.
Which Transmission Is in Your Truck
The year 2000 was the first model year of the redesigned Silverado, known as the GMT800 generation. Some heavier-duty versions continued on the older body style, often called the Classic or GMT400 truck. Transmission fitment depends on the truck's weight rating and engine.
4L60-E four-speed automatic: commonly fitted to light-duty Silverado 1500 trucks and some lighter 2500 configurations. It uses Dexron III, now superseded by Dexron VI. 4L80-E four-speed automatic: commonly fitted to heavy-duty 2500 and 3500 trucks. It also uses Dexron III, now superseded by Dexron VI. Manual transmissions (five-speed units offered in some trucks): these do not use Dexron ATF. Check the owner's manual or the transmission identification for the correct manual-transmission fluid.
The exact transmission in a specific truck can be confirmed in three ways. You can check the RPO (Regular Production Option) codes on the Service Parts Identification label, which is usually inside the glovebox. Here, M30 indicates the 4L60-E and MT1 indicates the 4L80-E. You can also check the owner's manual or ask a dealer to look up the VIN.
Dexron III vs. Dexron VI
Dexron is GM's licensing specification for automatic transmission fluid. A fluid licensed to a given Dexron version has been approved as meeting that standard. When GM introduced Dexron VI, it said Dexron VI could be used in automatic transmissions that originally called for earlier Dexron fluids, including Dexron III. Fluids sold today as Dexron III are generally no longer officially licensed by GM, so their labeling should be read carefully.
Universal or multi-vehicle ATFs often say they are "suitable for" Dexron III applications rather than being licensed. Whether such a product is equivalent is a judgment for the buyer. The more conservative choice is a fluid that carries an official Dexron VI license.
Before You Add or Change Fluid
Check the level correctly: on these automatics, check fluid with the engine running, the transmission at normal operating temperature, the truck on level ground and the selector in Park. Follow the dipstick markings and the owner's manual procedure. Confirm capacity for your transmission: refill capacity differs between the 4L60-E and the 4L80-E and depends on the service. A pan drain refills far less than a complete fluid exchange. Use the owner's manual or a service manual for exact figures. This guide does not supply verified capacities. Don't confuse the transfer case with the transmission: on four-wheel-drive trucks, the transfer case is a separate component with its own fluid requirement, which may differ from the transmission's. Inspect the old fluid: a dark color or burnt smell can point to wear or overheating that a fluid change alone will not fix.
Information Gaps to Resolve
Several details could not be verified for this guide and should be confirmed for your specific truck. These include exact fluid capacities, the correct fluid for each manual transmission offered in 2000, and transfer-case fluid requirements by drivetrain. The owner's manual, the glovebox RPO label and a GM parts counter using your VIN are the most direct ways to close these gaps.