Gen 4 – CVT fluid replacement and groaning noise

October 8, 2023

2010 2.5 OB with 188k miles started groaning mildly once placed into DRIVE after a cold start. The noise was intermittent and not very obvious at first. Over a couple of months the groaning worsened in loudness and was sometimes more obvious performing a 90 degree turn. The duration didn’t change much, lasting only about 10-20 seconds, but there was a rhythmical quality as if it was somehow related to some kind of rotating component.

The CVT fluid on this vehicle had never been changed. The car belonged to my wife for the first part of its life and then became mine. No excuses, just info. When I changed the fluid I was careful to measure how much I extracted and it was 4.5 qts which was lower than what I expected (~5-5.5 qts). So I was curious to see how much she would take in. After filling it while at temp 95-113deg F I ended up putting in 5.5 qts.

After doing this work the groaning ceased about 95%. My goal is to repeat this procedure in 1k miles to get a higher overall percentage of CVT fluid replaced and see if the volumes match or not and if there’s any further effect on the last of the groaning.

My questions are:

Is 4.5 qts extracted too low for CVT draining? (I understand there are 12+ qts total in there)
Would the unequal volumes of drain and fill signal a problem or cause a problem?
Is the (mostly) resolved groaning noise coincidental, correlational or causal because of an overdue CVT fluid replacement?

SIDE NOTE: I replaced with ENEOS CVT Model S fluid, which I read somewhere in the forums was compatible and safe for this transmission.

Thanks for any insight.

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