OldTires

As the title says, I drove in 3rd on the highway for about 50 miles. I didn't notice until I looked at the RPMs. The engine was doing about 3000-3500 at 75mph. I backed off the gas pedal and brought it down to 2500 at 55mph, trying to figure out what was going on. Then it dawned on me to check the shift lever. !@@##$%%

When I moved it back to D, the RPMs dropped back to normal, about 2000 at 60mph.

It has been a week since that happened, and everything seems fine. Could I have damaged the engine or transmission?

cruiser54

Nope. Carry on.

Last time you did a fluid change on the trans?

OldTires

Thanks, Cruiser.

I did a fluid change on the transmission last fall. About 3.5 quarts out, replaced with Auto Zone ATP fluid. It has been running really well since then.

cruiser54

You're good to go!!!!

OldTires

Thanks.

downs

No worries. I drove for hours and hours towing a heavier trailer and kept it in 3rd the whole time to keep it from hunting gears between OD and 3rd. 3000-3500 is well below the engines designed maximum speed so no worries. Your gas mileage probably suffered a little bit will the worst of it.

s346k

agree with above post. in 3rd gear i towed a dodge neon on a car dolly down the interstate with 4 passengers and luggage for a 3 day weekend with the ac on at 70 mph+ for 250 miles. this was on a 230k mile vehicle (30k miles ago). 0 issues. you’re fine.

Flock2Tribe

I have made the same mistake a handful of times. I have had no issues. I mean my trans IS gonna die soon but it was just as crappy before and after highway speeds in 3rd.

jshultz78

I went to the mountains a couple weeks ago, and I had to shift it like a standard on the uphill portions, stayed in 3rd most of the time, no problems.

jordan96xj

Driving in 3 is not a mistake. It is quite normal, and necessary sometimes.

On the XJ 3rd is actually direct drive (or D). So what comes out of the transmission is 1:1 with the engine RPM. It should almost always be used when towing (per Owner's Manual) and is a good choice when in hilly/mountain environments where frequent climbs and descents are being made.

D, or 4th, on your shifter (gear selector) is actually Over Drive (OD). So what comes out of the transmission is spinning just slightly faster than the engine RPM. Good for clicking down the highway at 60+ in a relatively efficient manner (RPMs around 1800-2000). Not so great if you need any type of extra power on demand (hence the downshifting).

Both 3rd and 4th benefit from the torque converter lock-up clutch (good for efficiency and temperature of the transmission oil).

Here is a factoid that most people might not know. 4th (Overdrive) does not have transmission braking in the AW4 transmission. So when you let off the gas on a steep descent, it is mostly coasting and the transmission/motor are not helping you slow down. 3rd (direct drive) -does- incorporate transmission braking. This is very handing when pulling a trailer or just driving in hilly/curvy environments, as you'll spend a lot less time riding the brakes. You can experiment this on your own on the highway, cruise at 60+ mph in both 3rd and 4th and let off the gas. Observe how much quicker your speed reduces in 3rd vs. 4th.

OldTires

Great info, Jordan. Thanks.