75W90 fully synthetic oil for 290DP - Too cheap?

[msimms]

Looking around for some oil for my outdrive, spec says fully synthetic 75/90 API GL5. Prices seem to be between £11 and £16 per litre. I then came across Smith & Allan on ebay. Seems very good value, maybe too good? It even quotes free delivery!

 

[Chris_d]

To be honest I would only buy the Volvo stuff, it contains a water inhibiter so if water gets it will hold it in suspension and still give good lubricating properties. Even the best car type gearbox oil won't have this, you could have water in the drive for a year without knowing it so its kind of an insurance.

 

[MapisM]

Seems very good value, maybe too good?

Mmmm.... There's a widespread consensus in the US that Mercury gear oil is NOT the best choice.
And I'm talking of peeps which really push frinstance Bravo outdrives to their limits, even into 3 figures speed.
Mobil 1 or Amsoil are considered the best alternatives. I did switch to Mobil 1 also for my B1, fwiw.

And since the claim from Mercury is exactly the same mentioned by Chris_d for Volvo, I don't think there's much more rationale behind it than trying to get a nice margin based on brand alone, from both Mercury and Volvo.
That said, I'd stick to the "original" oils as long as the outdrive is still under warranty, just in case.

Oh, and re. your quoted sentence above, yep, the price of that one really seems too good to be true...

 

[msimms]

To be honest I would only buy the Volvo stuff, it contains a water inhibiter so if water gets it will hold it in suspension and still give good lubricating properties. Even the best car type gearbox oil won't have this, you could have water in the drive for a year without knowing it so its kind of an insurance.

I've always used the Volvo oil too, I was looking for Volvo branded when I found the eBay site.

I'm dubious about the claim that the Volvo oil is able support water ingress. I wonder if it's been quoted that many times it's just regarded as fact. If it was the case I'd expect Volvo to mention it in the documentation. I've not managed to find it stated anywhere. Maybe others have, in which case I'd be happy to pay a premium. What I'd rather not do is pay over the odds for an identical or lesser product just because it comes with a Volvo sticker.

AMSOIL have a marine grade gear oil. They list figures showing it to provide the same foam stability with a 10% water mix. This I think would be worth paying more for.

 

[spannerman]

I don't believe for a minute the Volvo claims about holding water in suspension, of the many hundreds of drives I've serviced whenever there was water in a VP drive the gears had done a fine job of blending the oil and water into what looks like tthick evaporated milk, and the first thing we do when we see that is pull out the prop shaft and hub to inspect the pinion gear at the bottom of the vertical shaft as this one has the highest loading and often there are chips on the teeth as the oil hasn't been able to keep the teeth lubricated and the case hardening goes and bits start to come off, then we replace the entire lower section as the labour costs to replace the gear set and bearings with all the shimming, dismantling and rebuilding everytime you need to adjust the clearance isn't worth it.
Its cheaper and faster to replace the lower section and it has a 1 yr warranty, which you won't get on a rebuilt 8 yr old lower gearcase.