Gear oil in Bravo Raw water pump

[mr300z87]

Hi all, I have finally started working on getting the engine running in my project Sea Ray (see link in signature) and am at the point of putting the raw water/fuel pump assembly together. I know that the Merc Manual says to use their 90 wt HP gear oil in the fuel pump cam cavity. My question is can I use some 80w90 gear oil I have left over from when I changed the oil in my trucks rear end? As I do not have any Merc oil. These pumps are really price and I do not want to ruin it by runnin the wrong oil. As always all advice in greatly appreciated. Mike

 

[Bondo]

Ayuh,.... You Can do that, but I use Syn-oils in my drives, 'n would in that cavity too,.....

 

[mr300z87]

That is what I was leaning towards. I have a half a quart Merc HP gear oil stashed on the Invader so I will grab it while at the boat tomorrow morning. I was just being anxious and wanted get the pumps mated and ready to go on.