Just bought a ‘99 Civic with 138k on it. Don’t mind my ignorance, I’m a new car owner and trying to learn the ins and outs of these things. The car Needed some tlc got the power steering rack replaced, distrubutor was done recently as well as alternator. I did the blower motor and tires myself, it runs nice and purrs beautifully. Anyway I’ve noticed when driving in D4 which is what I typically drive in at all times that it takes quite a while for the tranny to shift gears, especially above 3rd it seems. I’ll be at roughly 4,000-5,000 RPMs sometimes when shifting at 3rd gear. Checked the transmission fluid, it looks brown but not black. I bought 4 quarts of genuine Honda fluid and plan on doing the job myself, but I’ve heard that it can be risky which has got me bugging that I’m gonna screw something up. I’m worried that mixing Honda fluid with whatever is in there right now will do it.

i don’t know when the fluid has been changed last or If it has been changed at all. Do you guys think it would be safe to change it given the circumstances and will it solve my problem? If not, what could be other potential causes of this to happen, and could things that would seem completely irrelevant to the transmission be causing this issue? Thanks for all the help.