Hello, I bought a completely stock and original 91 civic dx with the 5 speed manual. I changed the transmission fluid(old *** gear oil to penz oil synchromesh)recently and the car makes a louder whine in 1st gear than before. It’s makes this whine noise only while accelerating and only in first and the whine increases as I give it more gas. It also jerks a little when coming off gas even the slightest only in 1st. I’m wondering what the issue is if there is any(just watched a pov drive of the same car on YouTube and did the same as this in 1st only) and possible fixes. After researching I concluded it could be transmission, tps sensor, throttle body, or IAC valve. But none of the descriptions I read really fit my specific issue and I’m wondering is this is normal for this car as I haven’t owned any old civics before about a month ago. Help would be much appreciated as I’m not crazy mechanically inclined as it’s my first manual car at 21.

 

Can you hear the whine through your speakers or straight from the motor? I've heard of bad spark plug wires causing that issue.. also should use honda manual tranny fluid over anything else..