Just remember the strainer is just one of a list of things it could be so it might not cure it and it might not be necessary to fit a new one if you flush it but if you have one already i suppose it's one thing off the list, whilst you've got the sump off you could check the big end bearings for wear. Tightening torque for the sump bolts - 20NM just incase you didn't have the info.
Low Oil Pressure this might interest you big t to give you more of an idea of the different possibilities, there is a few.
Regards
Riggaz
