Hi, first time poster,

I recently took claim of a 1966 Mercury M-100, it has a 240 I6, with a 3 Speed manual transmission.

My question is, I'm trying freshen up the truck, and am looking for the oil for the transmission. I have original service manual and it says I need Rotunda Manual Transmission oil (Ford part #C3RZ-19C547-B) or 80W Standard Transmission Fluid R-139B.

I'm having trouble finding this oil at my local auto parts stores. Can someone give the modern brand or equalvilent??

Thanks in Advance

 

You probably won't find a straight 80w but a muli grade is alright. Look for something with a GL4 rating, don't use the newer GL5. GL4 is getting hard to find but I found some STA-LUBE brand at a local parts store. I believe you can get it from AMAZON also.

 

Use 90 weight gear lube.