You are in error. The final M in the part number has no effect on the actual part. Tohatsu/Nissan OBs do not go by tear of manufacture... rather model and in some cases serial number.
Hmm. 2.7% does seem a bit high. When was the oil pump rod last synchronized to the throttle? If the motor is really cold, you might use a bit more oil. But that sounds like the 50:1 ratio of WOT.