Question for 4 speed guys

The factory recommenced fill is ATF. That being said I tried synthetic gear oil (Mobil 1) and couldn't shift the car at all without crunching the syncros. I went back to ATF.

This past spring after following several threads on this subject I switched to Penzoil Syncromesh Fluid. This stuff is specifically designed for manual trannies and is compatible with all types of syncros.

It made a very dramatic improvement in the quality of the shifting. The tranny shifts quicker, smoother and with less effort than it did with ATF.