Transmission fluid recommendation. Redline, mobile 1, Toyota?

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Dec 9, 2007
Marietta GA
Fj60 with stock 4 speed manual transmission. I bought it new and for as long as I can remember I've been running redline synthetic fluid. I forgot to spec it last time and got mobile 1 synthetic this time.

Before the shifts were unnoticeable, super smooth and easy. Now not so much.

Is this all in my head?
Mobile 1 75w-90 gear lube is specifically recommended to NOT be used in transmissions.
Decades ago it was the cat’s meow of synthetic gear lubes but they’ve found (and I found) it doesn’t play nice with the synchros. The oil is too slippery so the synchronizers can’t grab the gears to slow them down - so the shifting gets un-smooth.

Use redline MT-90 if you want a 75w-90 oil or use Mobile’s Delvac Synthetic Transmission Fluid 50 if you want a straight (synthetic) GL4 gear lube (my favorite).

Even the regular ole Sta-Lube 80w-90 is fine.
The Redline MT90 is pretty well known for smoothening out shifting in old transmissions with brass syncros. You were pretty much using the best stuff you could from the get go.
Thanks for the feed back. I'm might be crazy but the transmission shifting doesn't prove it. ;)
I'll dump the Mobile 1 ASAP and go back to Redline.
You can also run a custom blend. In my '98 4Runner, I ran 2 qts. conventional and 1 quart synthetic. Now that it's older and tired-er, it I run full synthetic and it shifts well. It seems many people's experiences vary, depending on how they shift. In your case, I would start (as you indicated you would) with Redline and go from there.
I’ve ALWAYS used Walmart brand gear oil. Not at all saying that’s the best…just what I have used. These are not Maserati’s we’re driving.

Bought my ‘75 40 new, still a shared daily driver. Have had my 60 for 19 years now…400k miles. No issues using this stuff.
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