I have a johnson outboard motor that drips oil from the prop.why is this ?,maybe a seal is blown?

https://www.google.com/search?q=1957+johnson+outboard+10+hp+fuel+oil+ratio

What is the mix ratio for a Johnson outboard motor?

Any Johnson outboard motor built since 1964 requires a 50/1 fuel ratio. Motors built prior to that date require a 32/1 ratio, with the exception of a few fishing motors built prior to 1955 that use a 16/1 ratio.

Feb. 22, 2021

What is the mixing ratio for a Johnson outboard motor? - Mvorganizing.org

Hi.
See if this link forum helps you out.
Fuel mix ratio for Johnson motors
or this.
What is the oil gas mixture for 1994 25hp Johnson outboard motor Google...

drive shaft oil seal and possible shaft
take it to an outboard service shop as it may require special tools for the job

if water in rad has oil in it or smells , building up pressure in rad , water in oil !

Hi, mix the gas and oil at 50 to 1 and use two cycle outboard oil. Regards Phil.

I believe you got fishing !one wrapped between prop and seal. Remove prop and inspect for line and leak around seal. If not, than the seal under water pump plate is leaking your gear oil.

It sounds like you need to change prop shaft seal. While at it check water pump impeller (in sure it is still playable). Also change seal under pump wear plate.

Keep an eye on it and put a bucket with paper inside under the motor. You want to know whether the oil is burnt oil from the exhaust or gear lube. You should be able to tell from the color of the oil. Its kind of like soot in a chimney, the exhaust goes through the prop with the oil you added to the gas.

Here is a website where a manual for you outboard may be purchased.  Outboard Marine went out of buisness in 2000 and thus no parts of origial manufacture are support is available . Therir are secondary markets .    THe Lower case splits in half and their is a seal around the prop shiftm which is pressed in. The seal between the cases are cut o-rings which are placed and glued into place with gasket seal.
The water pump is located where the case splits a little bit higher. You must open the little port on the side and take out one of the screws to the connecting shift linkage to split the case. After splitting the case the drive shaft and water pickup tube(s) wil come out of the powwer head or the tubs may stick into the power head which is ok. Place the lower skag into a vice and remove the 4 or 5 screws to the water pump housing. Remove and replace impellor and impellor plate if available. If part(pieces) of the rubber impellor is missing flush out the tubes and the power head to remove them.   When reinstalling the lower unit use a flash light to make sure that the tubes return  to the proper place in the power head and the shift lever is resecured. If you need more assistance, just write back. I was an Outboard motor mechanic for five years about the time of your motor.