FYI- I have personally sent an email
to Yanmar, and did receive a reply stating and in reference to the screw-on filter # 129470-55703, which are for the 3JH & 4JH motors;
Thank you for contacting Yanmar.
The micron size is 5. After researching this with my Parts
dept. it appears that this is the lowest micron filter available from Yanmar.
Thank you and have a great day
Yanmar customer support
Customer / Technical support rep.
Engine Division of Yanmar America
Feb. 21, 2012