It's a 75/90 gear lube ....... 10W30 is motor oil. But it is used in older Volvo single prop drives, but not in Mercruisers
Get the Merc Hi Performance, it also has additives to keep water in suspension so if you do have a leak, the gears and bearings don't set in water only.
You can also use Amsoil Marine gear lubricant which (according to Amsoil), like Merc HP gear lubricant, is designed to continue lubricating when contaminated with up to 10% water. I don't sell it and am NOT an Amsoil cheer leader. It's just another synthetic gear oil for drives.
A local Napa Autoparts place sells it and it's easier for me to go there instead of driving further to get the Merc HP Lube.
Ditto on the Quicksilver High Performance. Don't go to Wally World, they carry the Premium, which is not what everyone here recommends (why, I don't know, but I listen to the advise here). And you'll need 2 quarts of it.
I have an '88 Alpha One. I believe thats a series one. Anyway the manual and the mechanic at the marina says the drive takes one quart of oil. When I fill it it takes about 1.25 quarts. Is this correct?
