Mitsubishi MTE2000D, Dig It 258 Mini Ex, Deere Z930A ZTR
Here is a link to a copy of the engine manual http://www2.burningzone.nl/data/mitsubishi/mitsubishi.pdf that I found online. Unfortunately, I don't think it mentions oil pressure but hopefully it will be of some help in other ways. Iseki/Bolens used this Mitsubishi engine in some of their tractors so the engine is actually made by Mitsubishi instead of Iseki.