Re: Rear Diff Fluid?

Posted by JWL On 2010/6/12 9:35:20

Dave, been doing a bit of gear oil shopping lately to service the '47 Custom. From what I have seen the "EP" rated oils are designated as "GL-5". While you can buy 5-gallon pails, most parts stores sell the gear oil in 1-quart containers. Much more convenient size. Based on recommendations from you and one other, I bought four 1-quart containers of Valvoline 85W-140 for the differential.

I am also looking at a replacement oil for the transmission and overdrive. In my owner's manual, Packard specifies 140 weight straight mineral oil for these two components and warns against using compounded or EP oils. 90 weight is specified for cold weather and hard shifting situations. My third gear syncro crunches a bit when shifting into high, and I am looking to see if I can get some relief by changing oil. One poster here recommended NAPA GL-1 90W (Part No. 65-201). He says it worked miracles on a '47 Super transmission that was crunching going into second and third. It is a mineral oil gear oil. Very difficult to find. My NAPA store does not stock it and will only sell it in 6 gallon cases because it needs to be specially ordered.

I'll let the forum readers know what I end up doing and how it worked-out.

(o{I}o)