Re: Mercury Mark 20 Rebuild

[mercuryspecialist]

Hello,

The gear lubricant uses a grease (versus an oil) originally. A very well sealed lower unit may retain gear oil, but otherwise, use of a suitable grease (Lubriplate 105 or John Deere Cornhead) is typically a better solution. The fill machine screw is on the port (tiller handle side) on the lower front of the "bullet" portion of the lower unit. The smaller vent machine screw is on the opposite side, but higher up, a little below the anti-ventilation plate underside. Both screws do have (as typical) a sealing washer which may be wise to replace. Induce grease (or oil) into the fill screw until it exits the vent hole to properly fill with lubricant. If you should like, I can share lower unit pictures through regular e-mailing.

Regards,
Joe