Differential Oil Change Concern

Finally got around to changing my differential oil on my 1988 (dana with only a fill plug) I believe it’s never been done by PO. Car has about 50,000 miles.

Managed to pump out 2 US pints of old oil. Added 3 pints until it dribbled out of fill hole. I filled it with Castrol Axle Limited Slip 80W-90 (not synthetic)

So based on a capacity of 3.3 US Pints, it was low 1 pint.

Any damage having run it 1 pint low all this time? And should I keep an eye on any differential seals if this means I may have a leak?

Thanks!

I had noise clatter and leak that was eliminated by changing the oil, adding the additive and cleaning the vent plug in my 95. This was several months ago and I have not had a problem since

Is it easy to get to and clean vent?

Don’t know about the Dana, but on the Salisbury the vent tube is above the fill plug.
You can unscrew the tube from the elbow quite easily.

You can spray some cleaner on it, but moving it around to dislodge gunk is the advice that was given to me at that seems to have worked well in my vehicle. It’s black, sticks out and above the fill plug.

Somewhere in the course of my shenanigans, I broke my vent off. Fortunately, I was able to replace the broken elbow with a generic pipe elbow and screwed the rest of the vent back into it.

Since you were a pint short and report no leaks, the vent plug is where your missing pint went. Differentials do get hot and the liquid will churn, so everything bubbles away a bit and the vent is the exit point.

If you plan on running hotter than the designers designed for, then having a longer, taller vent tube would be helpful.

kind regards
Marek

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thanks for all the feedback. So far no leaks, so glad to know it can actually be lost from the vent. Didn’t think you could lose 1 pint, but 50,000 miles/32 years, I guess a little at a time will add up.

I will not run hotter than designed, so should be fine.

I’ve only test driven a couple times since changing/topping up, but now under hard acceleration, my tire chirping from 1st to 2nd is a bit less, and the rear end doesn’t move like it used to during that chirp. So I guess my limited slip is working better! That should give me 1/4 second faster times on the drag strip :wink: