So I’m going to bring my 06 Corolla into this conversation to help support the pro-redline theory. Bought the thing with 150k for my kids to drive. They are out of the country right now so I’ve been driving it. Since acquiring the car, we have done all the maintenance on it. But as I’ve been driving it, I started wondering about the transmission oil and realized or figured it had never been changed. So I got the bright idea to change it and put mobile one synthetic in. That was a huge mistake! Prior the car shifted pretty much just fine, a little clunky from 2nd to 3rd or fourth the third. But for a car that old I didn’t have any concerns. As soon as I changed it to the mobile one, every time I shifted from third down to second, I was grinding like crazy. I figured it was the oil and called the local transmission shop, and he told me to switch to the cheapest convention gear oil I could find that met the original specs. I did that, and the shifting improved with less grinding, but when the transmission got extra warm from extended use, it would grind a little bit again. so after reading all the reviews about the red line transmission oil, I drained it a third time and replaced it with the red line. I have not had any issues since and the transmission is now shifting better than it ever has. So my conclusion is if there is extended wear in your old transmission, the red line stuff is a good way to go. Now I do have an 85 fj60 and I changed the transmission oil out about three years ago. Don’t drive it a whole lot but shifting down to third has always been a little rough. I usually just engage the gear extra slow or skip it all together. So I am going to, try the red line in the Land Cruiser and see if it improves that issue.
