Yes, I always used motor oil for my 5-speed manual tranny:
http://www.CRXSi.com/repair/transmission.oil.change/

Mark,

Thanks for replying, but you did not answer my question.

Have you or do you use 20W-50 motor oil in your transmission?

Anyone else out there with info is appreciated.

Tom,
Type of oil depends on a temperature of the year. Check the oil graph:
http://www.crxsi.com/reference/oil.htm
I personally use 10W40 all year-round.

Thanks Mark,

I was just going by my 1990 Factory Honda Helman service manual.

I didn't know or realize the Haynes manual had different info.

So based off of the graph, I can safely use 20W-50 motor oil in
my manual transmission with worn bearings, since I live in
Southern California.

Well Tom,
Can not tell you which oil to use. Bearings are not the main thing in transmission that undergo extensive wear and tear - gears are.
Even for Cali 10W40 is the best match according to graph - it gives you a better range in temps than 20W50.
Some people, I know, used a gear oil which shouldn't be a problem from my point of view as gear oil would require less tranny oil changes than motor oil as it resist gear friction better but Honda may have deeper knowledge on transmission design and moved toward motor oil for one reason or another as bearings design and load, gear shift design etc.
Apparently my local Honda dealer told me -- motor oil should be used in my CRX Si 1990 manual transmission back in 2000.

Honda choose motor oil because it is easier to obtain. 20w50 is close in viscosity to 90 gearoil at operating temp. check out bobtheoilguy on the web.