2008 Mazdaspeed3 132k miles. I swapped out my manual transmission fluid for Redline MT-90. I know that the user manual for the speed 3 says that the transmission takes about 2.6 quarts of fluid, so I bought 3 quarts of the Redline. Everything went fine, but i had read online and seen online countless times that you're supposed to fill up the transmission through the fill hole until it starts to overflow. First two quarts, no problem. I get to almost all of the bottle gone on the third quart, and it never overflowed through the fill hole. I was really confused, but I figured i probably shouldn't put in anymore despite it not overflowing, so I put the fill bolt back on. I'm now conflicted because I know that overfilling a manual transmission can cause damage, but I've ALSO read that you need to keep filling it until it overflows. So what do I do? I took it out for a drive, everything seems fine other than the LSD whine that comes with switching to the Redline on my vehicle, which is non-harmful. Yes, I put the Redline in the correct hole. I didn't put tranny fluid in my engine or otherwise. And yes, the drain plug was on before I put in the new fluid. 😁 Thank you!