What happens to the engine if I push the first gear or D1 to 25-30mph in an automatic? Will it ruin the trans? What's the recommended mph to change to second gear or D2, D3, and D4?

Car is a 1996 Honda Accord LX

 

It depends on what RPM you get to. 1 and 2 gear on the selector are not what you call a "D". D3 changes from 1-3 gear, but if you select 1 you are only going to be in 1st, 2 and you are only going to be in 2nd.

 

D3 as mentioned is for towing or to get a little engine braking on a long hills in winter. 2nd will remain in second even from a dead stop. Sometimes used in winter to ease out of a slippery situation. Wheels won't spin as easily. Only use 1st from a dead stop if shifting manually up the gears. Never shift down to first when moving faster than about 10mph. You're asking for trouble. If you're asking can you rev up to 25-30 in first before shifting manually, check out the manual. It gives recomended speeds for each gear. If the engine revs enough to get there, I don't see any problem. Just don't downshift going that fast.

 

Ah I see thanks for the info much appreciated.