It is fine to use Synthetic outboard oil. But be sure it is labelled
TWC-3 2cycle oil. TWC-3 is the standard that must be used dispite what brand you want to use. It should be clearly labelled.
Do not decrease the fuel to oil ratio for your motor!! Despite what some may tell you!!! Keeping your fuel oil ratio per manufactors recommendation will protect your motor and promote longevity!! Today's TWC-3 2cycle oils are superior to the oils manufactored at the time your motor was born, but please don't thin it out to 50:1 (It may last for a while and no troubles then one day at high cruising speeds that thing will seize up on you and the powerhead will be aluminum scrap!!)
The corrrect fuel to oil ratio is 24:1
5.3 ounces of TWC-3 2cycle oil to 1 gallon of regular 87 octane gas
or
32 ounces of TWC-3 2cycle oil to 6 gallons of regular 87 octane gas
Good luck and I hope she gives you a good ride!!!
Here is a link to a parts diagram for your motor!!
http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1959&hp=35
