Bring the level up to the FULL mark on the dipstick.
DO NOT OVERFILL!
When I talked with FMS years ago they told me to use 5W-30. I would use the lightest
oil which gave me the pressure I desired. For 9 years now I've been using 5W-30
synthetic with no problems and 55 PSI pressure at 2,000 RPM. I am currently using Redline
Oil for the higher Phosphorous level (
Zinc) they use. I know the Redline has the higher levels since I had it tested. I use a Moroso racing filter (29 microns) in the winter and a Mobil1 filter (10 microns) during the warm weather.
Bob