u/Dear-Ad-1577

I have a 1999 mustang v6 3.8l manual (T5), the car is at 188k miles and have no clue about the transmission fluid service history, I heard that changing the fluid can cause terrible damage at really high mileage but does that apply to only automatics ? or also my manual transmission ? I have no issues currently it shifts good but a change is starting to sound like a good idea, any help is appreciated 🙏🏻

To my knowledge the car has been running 5w-20 oil and has about 188.500k miles and doesn’t seem to be burning any oil, is there a specific oil I should look to buy for these engines such as mobile 1, motorcraft, Valvoline, castrol? also summers here in WA have been crazy hot these past years should I think abt switching too 5w-30 or stick to the 5w-20 oils (might as well ask since I have fallen down that rabbit hole lol)