No to the LSD additive in the transaxle.
A transaxle, as the name implies, is a transmission and a diff in one casing.
LSD additive makes the oil more slippery--so slippery the synchro rings don't grip properly and wear out or the gears crunch.
Use a non-LSD oil like RedLine 75-90 NS. If you get LSD chatter add a TINY amount of LSD additive and repeat if necessary until the chatter disappears.
The synthetic oil is also less viscous at low temps until it warms up, so if you live somewhere cold you might notice smoother shifting.
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