Guys need some help, I have spent the past two hours reading the many transmission threads out there and I have yet to get a clear answer. Here's my problem I have an 89 LX with a stock brog warner T5 in it and I have never had any issues with it up until now. I replaced the transmission fluid the other day because I had a leak at the rear seal, to make a long story short after replacing the seal and fluid I now get a grind when im shifting from 3rd to 4th? Not once did it grind ever until I replaced the fluid so could it be bad fluid? I used Dex III ATF and I swear as soon as I went for a test drive it started doing it. Could the fluid really have that much to do with it? Should I not be a cheapo and throw some Royal purple in there? Any suggestions guys I really dont want to damage the tranny if theres still hope. Thanks guys in advance