Why gear oil matters
Hypoid gears slide against each other under heavy load, and the oil film is what keeps those teeth from wearing. Heat from towing, grades, and long stretches of interstate traffic gradually depletes the additive package.
A light film of metal on the drain-plug magnet is normal. Chunks or heavy metallic content point to internal wear, which calls for a diagnosis before a fluid service.
How a Road Wrencher visit works
We need level ground so the fill height reads correctly, plus the right oil and modifier on hand.
- Step 1: We diagnose it. Which unit, which spec, any leaks, and whether the noise is a bearing rather than the fluid.
- Step 2: The exact shopping list. Weight, GL rating, quantity, and a friction modifier if the tag calls for one.
- Step 3: Flat-rate drain and fill. Correct level, magnet inspected, and the fill plug torqued.