Classic/Antique Car Repair: 1955 ford overdrive, ford shop, hot weather

Question
Mr. Benjamin
You told a man that was having a problem with his overdrive that he should be using GL4 140 gear lube in his trans & rear end. My trans is shifting above 40 also. But my 55 owners manual And Ford shop manual both say to use SAE 80 multipurpose lube. Are you saying that I should switch to the GL4 140. Thank you, Jim Dalian

Answer
When everything was new and tight, and the car had to work even in very cold weather, the thinner grease was needed, but even then, the thicker grease was often advised for hot weather.

In my opinion, if it is working OK with the current grease, stay with it, but if it has trouble engaging, try the thicker grease before spending money on an un-needed repair.

Dick