I just recently purchased a 2010 Honda Accord 2.4 liter. It has 150,000 miles on it and I was wondering is it safe to drain and fill the trans? Don’t know if it has ever been drained.

 

Are you having issues with the transmission, if not just do the drain and refill and you'll be fine. You don't want to do a flush.

 

Good maintenance approach since A/T service is easy to overlook for most owners.

Agree. Suggest using Honda ATF

Note that each drain/fill replaces ~40% of the fluid capacity. On the new-to-me A/T Accord I did two drains (since I was set up for it) separated by ~10 miles of driving to allow full old/new fluid mixing. So 6/10 x 6/10 = 0.36 old fluid fraction remaining after two; ~65% fresh fluid. YMMV