Grinding sound when transmission shifts under load

Maintenance/Repairs
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I’m writing to ask a question about my 1997 Mitsubishi Mirage. It has 98,000 miles on it.

I had my transmission fluid changed at my regular shop about six months (2,000 miles) ago.

For the past six to eight weeks, I have noticed that a light grinding sound comes from the bottom of the engine compartment. This sound happens briefly, for about 0.5 to 1.0 seconds, when the transmission shifts from first to second. I can try to find previous maintenance records if it’s relevant.

My question is, is it worth it to change the transmission fluid again? Is it possible that will take care of this? Are there any homeopathic cures?

I will note that the owner’s manual calls for “Mitsubishi Diamond ATF SP-II.” The shop didn’t have it, so I recommended a Valvoline ATF designed for imports, based on some searching?

So a second question is, would it be worth it to take this to the Mitsubishi dealer to get the official fluid? Thanks in advance for any advice.

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UPDATE: here is the transmission fluid change history.

July 2004, 76k miles: transmission fluid change. “MOPAR” fluid used.
July 2011, 93k miles: I purchased car
Sep 2011, 94k miles: transmission fluid change.

In the Sept 2011 invoice, it says “Diamond ATF SP-II” fluid was used. So I would like to correct my original post.