lwr unit oil?

[broken_line]

i have a old 5.5 hpp jhonson that me and my uncle replaced all the seals and bearings and drained the oil... does it matter what we put back in it as long as its gear oil??

[Eric Wettschreck]

Yes it matters. DO NOT put in regular 75-90 gear oil.

Regular gear oil is not formulated to handle the high speeds of the main drive shaft coming into the gearbox. Regular gear oil, dealing with a shaft spinning at high speeds will have a tendency to foam. Foam in the lower unit is bad as it will not provide the proper lubrication for your gears.

Name brands aside, it's very important to use gear oil specifically desinged for lower units.

[boatfixer]

Marine lower unit gear lube.

[theoilman]

Yes, there is a difference. A boat lower unit may have gears that look like minature auto differential, but the bearings and bushings are very different. Boat lower units turn at much higher speeds than your car or truck. Thus the foaming potential is much higher and needs different additives.

AMSOIL Marine Gear Lube (prod. code AGM) will outperform others - it will tolerate 10% water without loosing lubrication protection. (Available in 13oz tubes with squirt tip, and quarts.)