Synthetic Blend oil in 50 hp Force

[TLP Quantum16XB]

Does anyone use a Synthetic Blend oil in a 50 HP Force? The owners manual says No synthetic, but that manual is 30 yrs old.

 

[jerryjerry05]

Synthetic for the 50-1
Or in the lower unit???

I'd use it in both places.
The 50-1 the synthetic produces less smoke.
Amsoil is real expensive but real good.

The gear oil: make sure it's rated for marine service.