Ive noticed the past few months that whenever my auto tranny shifts into 4th or OD (at around 40mph and around 50mph respectively), the engine or tranny? will "shudder" and vibrate loudly as it settles into gear. Anyone know what this is?

 

Help? ANyone?

 

OD at 40mph is a bit on the low side, keep it locked out unless your doing 55 or more consistently. Have you serviced tranny? If the fluid is old get a fresh fluid change and add a tube of Lubegard shudder fix to it.

 

Mine does the same thing sometimes but not all the time. Car has 253K miles, Should I change the fluid, I was afraid of messing with it.

 

Yep you should, just a simple drain and fill 2 or three times over a few days and you will have fairly fresh fluid through the entire system. Just don't do a flush from the lube centers.

 

Ok thanks for the advice, how many quarts should I get, ill get the recommended NIssan matic fluid.

 

If everyone is talking automatic here, and it looks like it, do not change your transmission fluid if it is old, burnt, and already slipping.
It will actually speed up the problem due to the shavings and such being "washed" out and therefor making the clutches slip worse than ever leading to complete failure sooner than it would have happened if you just check the level and leave it alone.
Fairly well known issue for automatics.
Fair warning.

 

Iirc 4-5 quarts should take care of 1 drain/fill.

 

Mine isnt slipping just I havent changed it in a while, its not burnt either just wanted some input before I change it.