For the last 25 years I have owned Honda products with standard transmissions. The previous 5 Hondas I have had recommended changing the oil(30 wt motor oil)in the manual transmission every 30,000 miles. When I bought my '97 Accord the dealer told me not to touch the gear oil in the transmission. The car has almost 200,000 miles. Isn’t it about time I changed the gear oil? The shifting is a little sticky. Could be old age and not the gear oil. If I change it what weight do I use?
The dealer was very wrong but you are very lucky. The Owners Manual likely recommends replacing the fluid every 30k miles with Honda Manual Trans Fluid. Do not use standard oil. Change it and cross your fingers.
I would double check the owners manual. Do what it says as a minimum. If it is not mentioned, then I would have it changed every 50-100,000 miles.
Honda recommends changing the transmission gear lube every 30,000 miles on your vehicle. They also recommend that Honda gear oil be used. But if not available 10W-30 motor oil can be substituted. However they warn that using motor oil can result in stiff shifting.
I’ve always used 10W-30 motor oil in all the Honda’s I’ve owned with manual tranny’s, and never had a problem with stiff shifting.