The washer fell into the oil pan during the oil change.
Didn't realize it and put the bolt back without the washer.
Still shouldn't leak but really can't put the washer back without doing another oil change!
Will see if there's any leakage & if not then will replace it at the next oil change...
The quick link is to go with a new Shimano chain for one of the bikes SKMK has up in Oakland.