Which of the following might indicate a chattering clutch?

A chattering clutch is often associated with oil contamination on the disc facing. When the friction material of the clutch disc becomes contaminated with oil, it can lose its ability to grip effectively against the flywheel. This oil can come from various sources, such as a leaking rear main seal or a transmission input shaft seal. The presence of oil creates a slippery surface, which leads to insufficient friction between the clutch disc and the pressure plate, resulting in a chattering or grabbing sensation when engaging or disengaging the clutch.

The other options, while they may lead to different issues with the clutch system or overall drivability, do not directly correlate with the specific symptom of chattering. For example, low clutch fluid could lead to improper clutch operation but would not typically cause chattering. Worn transmission bearings may lead to noise or gear engagement issues rather than the specific symptom of chattering. High idle speed might affect the overall performance of the vehicle but does not specifically relate to the conditions that would cause a chattering clutch.