primary oil 1965 xlh

[cajun1957a]

Is there any advantage/disadvantage to over filling the primary side with oil?  My 65 uses the same oil as the crankcase.  I do know it is  for lubrication of the primary chain, but what if there is more in the primary side than reccomended by the drain hole height.  I may have over filled mine, yet i see no adverse effects.  Granted it is not half full either but a good half to one inch higher than the plug.

randy

[Lew]

The main disadvantage of overfilling is the extra build up of pressure when things start churning.  The higher pressure can cause the oil to migrate through seals and gaskets.

Lew 

[eglideic]

 Oil will leak out of your drive sprocket and shifter shaft oil seals.