Tranny And Diff

[jmfurgason]

How often should gear oil be changed on sm420 and 44 Dana . Just a Sunday driver ? Thanks be well be safe . JF:signthankspin:

[James]

SM420 or the Dana 44 - Maintenance Manual says check every 1,000 miles, drain and refill every 10,000 miles.

[jmfurgason]

Thanks James appreciate the response. JF

[GMC_Dude]

Remember that lubricants are vastly superior today as they were when those specs were written.

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[jmfurgason]

Hey Dude , soooo what would you recommend ?? Thanks to all JF

[tbucketnut]

For casual drivers, I replace gear oil every other year.

[jmfurgason]

I am using Valvoline 80w90 not conventional, every other year good?? JF thanks tbucketnut

[jmfurgason]

meant not synthetic CORRECTION JF

[thenonoman]

I just replaced what seems to be the original oil in the diff on my 65. I suggest a little more often than that. It was sludge-tastic. I expect to find the same in the trans.

[Jim A]

Since I found several places with very different capacities for the Muncie SM420 on my 1960 1500, I figured I would add one more.
Started with old oil just below fill hole and drained about 3/4 of a gallon jug .
I filled to the drain/fill hole through the shifter neck (since it was already off and much easier) with exactly 3 quarts.
At the current price of $10/ quart, it is nice not to buy extra.