However, generally speaking, you'll likely need either:
* 75W-90 gear oil: This is a common choice for many rear axles and is a good starting point if you don't know the specifics of your axle. Look for one that meets API GL-5 specifications. This is suitable for standard differentials.
* 75W-140 gear oil: This is a heavier-weight oil, often used in higher-performance applications or in hotter climates. Again, check for API GL-5. This is also for standard differentials, but sometimes preferred for heavier use.
* Limited-slip differential (LSD) additive or gear oil: If your Silverado has a limited-slip differential (often denoted by a sticker on the differential cover, or in your owner's manual), you'll need a specific gear oil formulated for limited-slip differentials. These often contain friction modifiers to prevent premature wear on the clutches within the LSD. This could be a 75W-90 or 75W-140, but *must* be specifically for LSDs. Don't mix regular gear oil with an LSD additive.
Before you buy anything, check your owner's manual or the sticker on your differential cover. The axle ratio and differential type are critical for choosing the right lubricant. Using the wrong lubricant can severely damage your rear axle.
