I have a pair of 01 250 ficht engines.The lower unit oil in one is a little off color,so I will need to change the seals out.My main concern was the amount of metal on the lower oil plug when I checked it.The magnet was wrapped in a layer of metal shavings length wise with a small ball of shavings on the tip.How much is normal to find after a 100 hrs or so?What is the best way to flush the lower unit and what is the best oil to use?Are there any special tools required to change the seals and is it fairly easy to do?Thanks.