best oil and viscosity for 69' 120 mercruiser I/O

[flyingd]

I am looking for the best oil and what viscosity I should use for my 1969 starcraft with the 120 hp mercruiser in it.

Any help is appreciated

 

[stonyloam]

Quicksilver 25W 40 is what Mercruiser recommends.

 

[m_steiger]

You cant get any better than Shell Rotella T 15w-40 from your local auto parts store. It has the proper amount of zinc needed for flat tappet motors that todays synthetic oils don't have because all newer engines are roller motors. Its the only oil I'll run in a flat tappet motor.

 

[achris]

An new oil thread. How novel. :facepalm:

Use any oil you like, as long as it's to spec, and spec is 25W-40, so anything that covers that is sufficient...

Chris....