I wouldn't run it in my car, it used to be common in the past but pretty much every trans builder now concludes it just doesn't offer the required protection.
Direct from Jon at TRE
Synchromesh/Synchroshift gear oils
While it has been found that the Synchromesh/Synchroshift type oils can sometimes improve the effectiveness of the synchronizers, allowing for faster shifts at higher rpms, this oil does not have enough film strength to ensure long gear and bearing life for the Mitsubishi transmissions.
Synchromesh/shift type oils are used in transmissions that are found in low torque applications that don’t ask much from the oil in regards of film strength. Transmissions that call for Synchromesh type gear oils are designed with wide gear shaft spacing which greatly reduces the force on the gear teeth and large bearings so that they can use these low film strength oils. The reason behind it is to reduce parasitic frictional losses and to improve shift quality.
If you have a weak synchro, you may want to try the “Synchromesh/Synchroshift†type oils but it is our recommendation that you use the proper GL rating that the transmission was designed to use and prepare for a rebuild.
