Hello, new to Subaru's, tranny issue

I bought a 1993 Impreza for a daily driver, and I've noticed that the tranny won't shift into its final gear (overdrive?) until I'm like 8 miles down the freeway.

What could cause this and how do I fix it?

Thanks.

is check engine light on? have you checked the fluid with car level and running in park. also is fluid a nice red or pink? if its brown yellow or dark it needs changing

the fluid looks good, and full. it smells fine. and no check engine light.

might have to take it to a tranny rebuild shop and have them check it out. most will test drive for free. but its programmed not to shift into od and torque converter lockup till fluid reaches a certain temperature, its possible your fluid temp sensor has failed

Any idea where the temp sensor might be on this car?

I would do drain/refill for starters and see what happens.

Good luck,
Sam