Volvo Penta 290SP-A Wrong oil?

I have just changed the oil on my 290 SP and used 75w90 GL5, as that is what my previous DP drive used. I now realise that I should have used engine oil sae30 or 40. Should I change it, or is the synthetic GL5 actually a better oil anyway and best left? Thanks

J25ELCI said:

I have just changed the oil on my 290 SP and used 75w90 GL5, as that is what my previous DP drive used. I now realise that I should have used engine oil sae30 or 40. Should I change it, or is the synthetic GL5 actually a better oil anyway and best left? Thanks

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Your AQ series 290 SP s/p (single prop) drive requires either 30W non-detergent engine oil for cold water use, or 40W non-detergent engine oil for warm water use.

Just behind the lower unit's "driven" gear, there is a die cast aluminum slinger pump impeller.
The driven gear operates this impeller via one or two small spring pins.
Heavy gear oil (GL-5 for example) can over-load the impeller and cause the small spring pins to shear.
When/if these pins shear, the slinger pump no longer delivers gear oil to the transmission (upper unit).

Here is a better view of the die cast impeller.
This should better explain how it mated and pinned to the driven gear.

RicardoMarine said:

Here is a better view of the die cast impeller.
This should better explain how it mated and pinned to the driven gear.

View attachment 22128

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thanks Rick. Looks like ill be changing the oil again.

Is there a chance that this s/p drive was operated with the GL-5 oil?
If so, I can show you a fairly easy way to determine if the slinger pump is still working.

No I have not run it since putting the GL5 into the drive, but would still be interested in knowing if the oump is working, as the drive is new to me and I have no idea what oil was in it before. Thanks

Engine OFF.
Tilt the drive up.
Remove the shift mechanism housing (you will need one new O-ring for this).
The oil level should be right near spilling out.

Spin the prop fast in one direction.

Look to see if the oil level comes up any.
If it comes up.....the pump is likely OK.
If it does not come up nor move, the pump may be bad.


If the slinger pump is working, it will provide the cooler lower gear unit oil up to the transmission, where it then gravity feeds back down.
If it's not working...... well, you get the idea!



By the way, the Duo Prop uses one of the lower unit "driven" gears to pump the oil up through specially designed ports.
No slinger pump impeller in the Duo Prop.





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That's really useful info. I will check when I, next working on it. Thanks