Volvo Penta 5.7 GXi – Fluctuating oil pressure readings

[AirStage]

Hi everyone,

I have a question about the oil pressure on my Volvo Penta 5.7 GXi. I’ve noticed that the needle sometimes fluctuates quite a bit.

On a cold start, it’s stable at around 40 psi at idle. After about an hour of cruising, idle oil pressure drops to about 10–20 psi and fluctuates noticeably. At cruising speed, pressure is around or just above 40 psi, and at higher speeds it’s about 55 psi.

Before the last maintenance, I thought the readings were more stable, but since I’ve only recently bought the boat, I can’t fully rely on my memory.

Operators manual states 20psi idle and 70psi WOT on operating temp. i'm not that far off then?

Oil is 25W40 FS.

Is this variation normal for this engine, or should I be looking into possible issues?

Thanks in advance for any advice!

[Pilotmike]

Mine bounces around quite a bit. Most likely the sending unit sensor. I bought a replacement, but I haven't yet installed it. has anyone replaced these before? If so, can you describe where it's at?

Thanks

MV