replacing the engine in a 17 crv. also had torque converter shutter, did the 3 change thing did not improve. so while engine is out will change the converter. it is assumed that oem will have the best fluid. But after talking with some transmission shops they seem to have a different opinion. So may go with alternative fluid. Seems no one has done a deep dive on converter fluid and failures which seem to be common now in many different cars. I drive my cars till 300k and converter s were never and issue. My understanding is cvt's generate a lot more heat. therefore degrade fluid. and thus converter failure