TOPIC: Recommended lower unit lube / oil question...

Hello!

I have purchased a 1970 Mercury 500 50hp Kirkhaefer 4 cylinder motor. It appears to be in good shape.

I have a couple of questions that I would like to get your input on...

1) What lower unit lube do you guys think works well in this motor?
2) How often should I expect to have to put more lubricant into the lower unit?
3) I know I need to mix 2-cycle oil in with my gas. I can't seem to find the ratio for the mix.
4) What brand of 2-cycle oil do you prefer?

Thank you for your answers and patience with my questions!

Outboard motor gear lube , available at any boat dealer and even CHINA mart.

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Lower units are sealed and once full all you need to do is to make sure no water gets in.

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Lower units can be pressure tested to check condition of seals / shafts.

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Mix oil and gas at 50:1 using a good quality oil ( TCW-3 rated )

And,...If you find there is water in the gear lube or the gear lube is clean, but quite low you should definitely get the gear case pressure tested, identify the faulty seals, and R&R the thing as THAT is the weak point and primary cause of failure in that model and many other model lower units.
Maintain it, replace the water pump impeller every 2-3 years, and service the prop shaft by removing the prop and greasing the shaft annually.
Thom