W58 Transmission Fluid Change - Filling Through Shifter Hole When Fill Plug Is Stuck

Transmissionintermediate✓ OP Confirmed

Problem

W58 transmission fill plug was overtightened/rounded by a previous owner, making it extremely difficult or impossible to remove for a standard fluid change. The transmission also exhibited noise and poor gear selection due to old or low fluid.

Suspect noises from transmissionPoor gear selection feelReverse gear clunk from differentialTransmission fill plug stuck/rounded and unable to be removed

Root Cause

Previous owner or mechanic overtightened the transmission fill plug, rounding the head and making it nearly impossible to remove with standard tools. The transmission and differential fluid were also old/degraded, causing noise and poor shifting.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted April 2022 on SupraForums.com