Chirp during turn

I've recently noticed a squeak/chirp coming from the rear of the car during slow, tight turns. This may have been happening for a while, but not noticed due to tire noise. (The Yoko YK580s are a lot quieter than the Goddrich Super Sport G-force they replaced.)

Is this normal? I'm guessing that it means that I need to change my diff fluid.

Thanks.

Could be diff, or rear springs or wornout bushings or wornout exhaust hangers. Lots of possibilities.

I changed the fluid, put in Mobil 1 75w90. What came out looked like motor-oil after 5,000 miles. The differential acts more like an open diff now than it did before, and the chirp on turns is gone. If I floor it coming out of a turn, the inside wheel will kick up gravel or whatever if the pavement isn't clean, though.

I did learn to check to ensure that the washer is on the drain plug before adding the new fluid. Unfortunately, I learned that lesson a bit later than would have been convenient. Thankfully, I had a hand pump so I just pumped the new fluid back into the bottle before putting the washer back on the drain plug, then refilling the differential.

Hope this helps someone.