Transmission going bad on IS250?
 

I have a 2007 Lexus IS250 AWD that i recently bought with 168k on the dash and i have been noticing that when i start driving the car it wont shift into 6th gear until the car is fully warmed up. It wont even let me shift it to 6th manually. I have to drive about 2 miles before it starts shifting into 6th gear. Anyone else notice this with their IS?

Yes, that's completely normal behavior; your car did the exact same thing when new.

Check out "step 3" in the guide from ClubLexus: https://www.clublexus.com/how-tos/a/...to-gear-365738

I had the same thought with my IS350. Very interesting feature for sure.

Trying changing transmission oil.

Why? Preventing the transmission from shifting into 6th until the car is warm is implemented in software, and is completely normal behavior. I think it's even mentioned in the owners manual.

no matter what car new or old 2001 or 2016 model i let the car warm up for at least 5 mins before i drive, i shift to any gear without a problem, but ya my TRD solara won't shift to gear 4 if the engine isn't warm enough same as my Lexus is 250 AWD every morning it won't shift to gear 6 within 1 mile if i don't let it warm up like i said.