BlueSpeed

i've searched and found that the fluid capacity for a manual Z51 transmission is 4.1 qts however, all previous posts state that the manual transmission only takes 3 1/4 - 3 1/2 qts to refill even when 4 qts drained out, does the factory "overfill" the transmission, how much should I put back in?

I've noticed the same thing with the differential - about 2 1/4 qts drained out of mine even though GM states that the capacity is exactly 2qts?

???

Miaugi

In both cases you should refill untill fluid starts to run out of the refill hole. This of course presumes the car is completely level.

mlongo99

Capacity is just ovet 4qts, but not all of it will drain out, so you will only need about 3.5qts to fill it back up.

As for your diff, was the car level when you filled it? Mine took less than 2qts to refill.

BlueSpeed

my concern was how could approx 2 1/4 qts drain out if the capacity of the differential is 2 qts? I wanted to put the same amount back in that drained out. Am I going to run into the same situation with the manual transmission?

JJC5

You probably know this but in case you have Z51 option, there is a trans. cooler and that will take more volume at the fluid change than non Z51. After you fill the trans., it should be run and then rechecked because the trans. cooler lines might have air in them from the draining.

mlongo99

It's a strange situation, so I don't know if you'll see it again. I guess it could have been over filled. Either that, or you didn't measure accurately. The important thing would be that it gets filled up to the fill hole, while level. How much did it take to fill the diff back up?

BlueSpeed

I used a measuring cup so I think I was pretty close to getting an accurate measure, approx 2 1/8 qts drained out of the differential, I put that much bacl in but I lowered the front of the car a bit to put in that last 1/8 qt. as it started dripping out.

After reading some of the prior posts, I am wondering if I am going to encounter the same situation with the manual transmission?

eurostyle

Another question I have is what's happen if you change brand. Is the new oil going to be compatible with the OEM oil left in the tranny?

NORTY

Providing the new oil meets the GM spec, you should be all right.

NATO mandates that "like oils are compatible with like oils."