Earlier today, I had the left front half axle and front brake rotors and pads replaced by a small independent local mechanic shop. I don't know why, but most of the transmission fluid leaked out when the mechanic pulled the old half axle off. After replacing the half axle and brake parts, he added 80W-90 gear oil to the transmission.

I don't have the owner's manual for this car, but I have a manual for a 91 Accord and it specifies 10W-30 or 10W-40 for the manual tran. I suspect the recommended oil for the '88 may be the same as for the '91. I don't want to leave the 80W-90 gear oil in it if it is the wrong oil.

If someone reading this has a manual for '88 Accords, can you confirm for me what the manual recommends for manual transmissions in '88 Accords?

I believe you are right.
My '1987 Accord' manual tells me use the proper viscosity for the climate you live in and the chart beside it lists 10W-30, 10W-40 along with 20W-40 and 30.
I'm looking at my automatic transmission problems right now and I'm sure I've seen posts saying just straight motor oil for manual trannys.

OK, thanks for that info, mdhbhouse. I think I'm going to call the technician and tell him he put the wrong oil in the transmission.