My Corolla’s 5 speed manual trans fluid hasn’t been changed in 5 years. Much of that time the car was only idled in the driveway (due to Covid/CA emissions testing complications). Now it’s back on the road, got to wondering if a manual trans fluid replacement is worthwhile? The fluid level is right at the top where it should be, and looks visually clear, like new, no used-oil odors, etc. I’m thinking no hurry, this job can wait for another year. What do you folks think?
Could probably wait another 5 years.
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How about the mileage? I do mine every 30K, but I’m compulsive.
I’ve never changed trans fluid/oil in anything in my long life and no regrets.
Can’t hurt but probably not necessary. What does the owners manual say? The owners manual for my manual transmission Nissan has no time or mileage recommendation for changing it, just check for leaks every 10,000 miles. I changed it anyway at 50,000 miles and what came out was still clean and clear.
Manual trans and diff oil don’t need to be changed any more than 100k miles but I do it at 50K…
My track car gets diff oil changed every 2 years because it gets quite hot.
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Your manual transmission has a dip-stick?
As for changing…I think it depends on the vehicle. Most manual transmissions use gear oil. This type of oil can easily last 100k miles or more. GM uses Dexron-II (ATF) for their manual transmissions. This is very thin oil and I wouldn’t recommend going over 50k miles. An even less if abused.
I am always acutely aware of any strange sounds coming from under my car, like: “a thump, a thunk, or a clunk…” or I when the engine goes, “vroom, vroom,” and the car no “go’s, go’s…” Then there is also when I see this lying on the ground behind my car, then I take it in for service… L 
L . . .
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You get 2 years out of a diff on a track car? 
That looks like an A727 (except for the bell housing?) that someone did a burnout and then the tires suddenly hooked shocking the rear sprag gear in the transmission causing it to fail causing the front drum to over rev and explode… The stock drum will explode at 9000 rpm (aftermarket billet drums are good to 15,000 rpms or 7500 engine rpms), the engine only has to be turning around 4500 rpms when this happens… If you put it in low gear it applies the low/reverse band and that holds the reverse drum greatly from moving around and keeping the rear sprag from breaking… Just a useless bit of info that nobody but street/strip guys care about… lol
8.8 axle with a Torsen! Ask for it by name! Gear drive limited slip instead of clutch packs. Maintains limited slip more consistantly than clutch packs.
And road course driving isn’t as hard on a diff as drag racing or autocross.
No dipstick.
Thanks for the comments everyone. I last replaced the trans fluid in 2019, about 15 K miles & 5 years ago. Based on your comments I’ll be deferring this job at least until next year.
Why not go 50k? MT oil doesn’t age significantly.
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Ahh yes. I recall installing one of those a couple years back. Strange customer, had a bone-stock Ranger or S-10, 2WD, wanted the diff installed and set up. I asked if he had plans for the rest of the drivetrain, he said nothing other than lowering 2 inches. Odd.
Change the clutch fluid when you do the trans.