Synthetic is required. And not just any synthetic, but the one from the MB dealer. Changing the fluid also requires a special tool that measures both fluid level and temperature and must be purchased from the dealer. The car does not come with a dipstick, and measuring the fuid at the proper temperature is critical.

Changing the fluid on this beast is something I would not do myself, so I had the dealer do it. The transmission ended up being rebuilt less than 5,000 miles later. Whether due to the fluid change or not, I cannot say. But they are mighty expensive and I wouldn't tinker with one.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References