Oil pressure sender unit

Hi guys sorry if this is in the wrong section but I urgently need to know how tight the oil pressure sender should be, I know that's a bit of a strange question but I can't get the bleeding 17 spanner on to tighten it I've tryed all the positions flip the spanner from top on the side everything have I missed something? I'm using a normal 17 halfords spanner. Oh and by the way my oils one was faulty (I think) so replaced it to see why I was getting sudden drops of oil pressure when cold. For eg it would go from 4.5 to 2 in about 4-6 mins can't figure it out anyway please advise any easier way to tighten the oil sender
Thanks in advanced

Going from 4.5 when cold to 2 after a few mins of warming the car up is correct?

As above mate , im on my second R and they have both done the same. At least you have a spare sender lol merry christmas

Lol thanks guys for putting my mind at rest merry Christmas and happy new year

hand tight anyhoos. about a quarter turn once you feel it tight.
6-8 from cold.
~4 on throttle once hot
2+ on idle

Thanks you so much guys appreciate it