fluctuating oil pressure AQ225D

[Ciera2450]

Hey guys,
My oil pressure guage drops to about 10-15 at very low rpm and then jumps up to 50 or so when throttle is increased. This has happened the entire time i've had the boat and have been working on tons of other things. Now its time to address this issue. I seem to have plenty of power and the motor sounds smooth. What are some things I need to be looking at for this issue? Or is this normal?
Volvo AQ225D with a 280drive. 380hours on the meter.

 

[bruceb58]

Re: fluctuating oil pressure AQ225D

Pretty normal. Does this happen with engine only warmed up or at cold as well?

When I switched from straight 30W dino oil to mobil 1 15w50, my oil pressure stopped dropping so much. That's not the reason I changed but that is what happened after I changed.

 

[Ciera2450]

Re: fluctuating oil pressure AQ225D

I don't notice as large of a fluctuation when cold, more noticeable when warmed up. I AM using 30w oil in the motor and drive. Next oil change i'll give the mobil1 a shot. I just wanted to make sure i wasn't damaging my motor in some way. The pressure shoots right back up as I increase the throttle but the drop when I pull the throttle back concerned me.
She is "burning" a slight amount of oil for some reason. Its only 30years old ya think it wouldn't! lol At the end of last season when changing the oil during winterization the oil was about 1/2quart low. Dunno if that SHOULD be a concern or not, i've had old junker cars that drank oil like I drink beer and they ran fine.
Edit: I put nearly 80hrs on it last season

 

[Scott Danforth]

Re: fluctuating oil pressure AQ225D

I would put a mechanical gauge on the engine and compare to the gauge. however the oil pressure does fluctuate with engine temp and RPM.

 

[bruceb58]

Re: fluctuating oil pressure AQ225D

1/2 qt in 80 hours is pretty darn good!

 

[Ciera2450]

Re: fluctuating oil pressure AQ225D

thanks scott and bruce! I appreciate your input and I think i'm just being overly cautious. (new engines aren't cheap!) I'll try a guage right at the engine and see if the dash guage readings are even accurate. As I said, the motor runs smooth with no ticks or knocks.

 

[bruceb58]

Re: fluctuating oil pressure AQ225D

I think what you see will be going away with the synthetic. What I noticed was that as the 30W oil got older and older, the low oil pressure issue worsened. I don't see that with the Mobil 1.

 

[Ciera2450]

Re: fluctuating oil pressure AQ225D

Thanks bruce, I'm going to change the oil this weekend and check it out. You still keep 30w in the drive right? or would the synthetic be better?

 

[bruceb58]

Re: fluctuating oil pressure AQ225D

Thanks bruce, I'm going to change the oil this weekend and check it out. You still keep 30w in the drive right? or would the synthetic be better?

Yes 30W in the drive.