The Sonata manual says to change the transmission fluid at 105,000 miles. My car is almost reaching 120,000 miles. Do you think it would be okay to wait until my next oil change to change the transmission fluid even though it is dirty? Or will it not last? (I don't remember having the transmission fluid changed before).

Any thoughts? Thanks.

Edit: Oh, and I have a 2008 Hyundai Sonata.

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Do you ever drive short distance of less than 5miles (8km) in normal temperatures or less than 10miles (16km) in freezing temperatures?
Do you drive on rough, dusty, muddy, unpaved or graveled roads?
Do you drive on salt-spread roads during the winter?
Do you ever drive in heavy traffic areas over 90°F (32°C)?
Do you ever drive on uphill, downhill, or mountain roads?

Then your car is considered to be driven under severe driving conditions and you should follow the Severe Driving Maintenance Schedule. And in that case the trans fluid should be changed every 30,000 miles. I'd say you past due 3 times already.

 

Flush or drop the pan and fill?

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Personally, I like flushing because it replaces all the fluid but that's not a requirement. A drain and fill is usually good enough. But that's if it's done every 30k miles. At over 100k, it might be worth doing a complete flush. Again, that's a my personal preference.