If a 2000 grand Cherokee has grinding noise when you turn corner that changing the oil in gearbox stopped for few months what could eliminate it?

The fact that an oil change in the gearbox temporarily stopped the grinding noise strongly suggests the problem lies within the transmission itself. The temporary fix points to a lack of lubrication as the root cause, but the return of the noise indicates it's likely more than just low oil. Here are several possibilities that could eliminate the grinding noise in your 2000 Grand Cherokee:

* Low Transmission Fluid: Even with a recent oil change, the transmission might still be low on fluid. A leak could be causing this. Check the transmission fluid level and condition. Low fluid leads to insufficient lubrication, causing grinding.

* Worn Transmission Components: The grinding could be due to worn gears, bearings, synchronizers, or other internal transmission components. The oil change might have temporarily cleaned or lubricated these worn parts, providing a brief respite. This is the most likely and unfortunately, the most expensive potential problem.

* Transmission Fluid Contamination: The transmission fluid may be contaminated with metal shavings from worn components or other debris. A simple oil change might not completely remove all contamination. A thorough flush and fill might help, but worn parts will still cause issues.

* Low Differential Fluid (Possibly): While less likely given the "gearbox" mention, a low differential fluid level could cause grinding noises during turns, especially since the differentials are heavily used during cornering. Check the differential fluid level as well.

* Clutches/Bands: Problems with the transmission's clutch packs or bands can also cause grinding noises, especially under load during turns.

To eliminate the grinding noise, you should:

1. Check and top off (or replace) the transmission fluid: This is the cheapest and easiest first step. Pay close attention to the fluid's color and condition (it should be reddish and relatively clean). If it's dark, burnt, or smells burnt, it strongly suggests internal damage.

2. Inspect for leaks: Look for evidence of transmission fluid leaks around the transmission pan, seals, and lines.

3. Consider a professional inspection: If the grinding persists after checking the fluid, a mechanic specializing in transmissions should inspect your Grand Cherokee's transmission. They can diagnose the problem accurately and recommend the appropriate repair (which might range from a simple repair to a complete transmission rebuild or replacement).

Ignoring the grinding noise will likely lead to further damage and significantly higher repair costs down the road. The sooner you address it, the better.