Throwing oil

i really dont worry about the leak near the shaft because with out the oil in the shaft there is a possibility that the shaft can jam. even dewalt new hammer when you purchase it come with the grease/lube like a toothpaste size. this is to lube the bits for the purpose the bit/shaft can move freely & also can hammer freely. our you can do is to dis-assemble the front end sleeve & remove the excess oil.will i agree weather can also change the viscosity of the oil. varsol cleaner can do the trick available at walmart.