I changed my D16Y7's manual transmission's fluid for the first time doing it myself. Have you ever seen old transmission oil this color? It looked like really old engine oil to me but don't know a way of finding out what the previous owner or serviceman had put in there. The new fluid I put in was Honda's MTF. Since the old oil was so bad, should I change its fluid again after I drive a week or so? How would you describe the old oil by the pictures?

I dropped some magnets in the old oil to attract metal fragments and found some. However, I don't know what's a normal find and not normal since this was my first time. Found little fragments here and there.

New vs old...

old...

metal fragment gathering...

old, again...

 

seeing as how most people used (and still do) engine oil in their transmission (which is fine for Civic drivers), it probably is really old engine oil that wasn't changed for a couple years. You should have done a flush but just use what you got for a few weeks, drain a little to check if there is any shavings in your new oil and if there is just drain and replace.

 

That looks pretty normal to me, 10w30 motor oil is an acceptable substitute for the genuine MTF. I have run motor oil in several Honda transaxles with no ill effects. There are many opinions on this website about running motor oil in the transaxle, but personally I have never seen any harm come of it. I did recently drain and fill my 96 EX with proper Honda MTF, just to see if it made a difference. I think it feels nicer to shift.

If the fluid has not been changed in awhile, there will be some fine metal particles in there. There is a magnet in the case to catch them too, and some folks have retrofitted a magnet to the drain plug. If you find discernable chunks of metal, you may have a bearing going bad. The input shaft bearing is a common failure item, and you may find pieces of bearing cage in the fluid if that's happened. The fine gray powdery stuff is no big deal - normal.

 

That old oil doesn't look bad IMO.

Here in new Honda MTF next to old Honda MTF from my Y7 tranny after only 16k miles:

http://www.flickr.com/photos/26016203@N03/6286291373/
Bearings are toast me thinks.