oil weight

[AC1957]

I'm sure its on this site somewhere but what's the preference for oil weight?
Its in a 51 cj 5. Only warm weather use. Would have used 10-40
Anyone using synthetic?

[AC1957]

its actually a 57

[TJones]

I'm sure its on this site somewhere but what's the preference for oil weight?
Its in a 51 cj 5. Only warm weather use. Would have used 10-40
Anyone using synthetic?

What engine is in your 57 CJ AC?

Bmorgil will jump in at some point today but he is the Guru on oil and anything engine or drive line related.

[LarrBeard]

My '48 has the F-134 retrofitted and Doc Dana (BMorgil) stgrongly suggested that I try Valvoline VR-1 10W40. I did and I like it.

It is a semi-synthetic oil, not too expensive and I will end up changing it every couple of years and using the drained oil in the mowers because it still is pretty clean. (The mowers are front yard trash day pick-ups)..

[AC1957]

F-134 rebuilt in the 80' and lightly used. Odd but it wasn't set up with an oil filter which I am planning to address.

[bmorgil]

AC, for the weight you want to stick the recommendations from the factory. Below is a picture from the manual for the CJ3B, CJ5 and CJ6. I would use a 30W or a 10W-30 oil unless the ambient temperature drops below 10 deg Fahrenheit or so. If it gets really hot outside you could go with a 10W-40. This link from the site has more information on the correct type of oil.

https://willysjeepforum.kaiserwillys.com/showthread.php?2419-The-Right-Motor-Oil

[The Beef]

Rotella 15 40 diesel oil . It has zinc.