3.0 Manual Transmission Oil Change?

[x5toker]

Hi there:

I'm a recent buyer of a 2002 3.0 5-speed with 94,000 miles on the clock. After the first engine oil change, the mechanic took it for a spin and said the transmission was a little 'whiney' but that I shouldn't be concerned. He also said that the transmission fluid was lifetime and that changing it would not be beneficial to the car or the sound...

I've done searches on here, but I can't find any good advice for the 3.0 manual -- only articles and guides for the automatic!

So now I'm seeking ya'lls advice... What do you have to say about changing the fluid in the 3.0 manual? Is this something I can do myself (I have amateur level car skills). Does a guide exist for this process somewhere on the internet?

Thanks so much!