Will have the car for one whole month on October 22nd. Have not made first payment. I go to leave my street tonight, and my transmission will not shift out of first gear. I changed the fluid to High Mileage about 2-3 weeks ago after I first got it. Fluid looks fine - level is touching bottom of full mark. It shifts perfect into reverse, neutral, park, drive. No matter where I put it D-3-2-1, it will not shift out of first now.

What it did do - after it warmed up, it will start to go, then hold back, then start to go again with steady pedal pushed without moving my foot.

My father tells me to check it for a leak in the vacuum modulator hose (if it even has a modulator). He says I should add some lucas before I take it to the tranny shop.

Can anyone over me insight?