Hi
I checked my Hyundai oil and it dripped pretty yellow.
I was expecting a black colour.
And seemed pretty lubricative with my fingers.

Maybe, maybe not. Not the answer you were looking for but, without an analysis no one would know for sure. With 150K miles odds are it is spent and due for a change.

I'm not knowledgeable in this but i am going to assume because there is no filter the manual transmission the oil wants the dirt to settle out making the fluid appear clean. Also different anti wear additives or viscosity modifiers are probably wearing out. I'm sure the gears inside are causing the fluid to shear out of spec

I mean, you're probably going to get told to send it out for analysis...that color doesn't mean a thing...follow the owner's manual, etc, etc, etc. But I do think manual transmissions are probably "easier" on the fluid than an automatic transmission.

An automatic transmission fluid has to do more things...it has to perform hydraulic tasks, it runs hotter, it has to allow friction between the clutches, it has to lubricate, and it has to fight heat. The manual tranny has to lubricate and provide protection while supplying smooth shifts. It's generally a "thicker" fluid. It runs cooler. Having said that, I'd change the fluid. You'd spend the same getting an analysis done and changing the fluid isn't going to "hurt" anything, like it might do in an automatic transmission because of the friction qualities.

Does the owner's manual give you any instruction as to when to change it?

When I had manual transmissions, I would change about every 30K or when the shifting got a little clunky.

I'd just change it.

Yep. 30K miles max with a manual transmission.

Saturn recommended a change at 6k (to get initial wear particles out) then never again.

It was of course a mere 2.3 quarts of dexron so a change could be done for under $10.

Trannies don't get screaming hot-- they'd better not-- but if you drain it after a nice highway run the engine heat may have conducted through the bellhousing. This would thin the oil and shake up the junk on the bottom.

300k+ miles on the manual gearbox in my Capri.

Until 2016 it had never had a single oil change, still going strong with absolutely no problems, i changed the oil in it again this September which improved the shift quality.

Thx for answers.
To tell the truth i tried to change today but the tool was weak to open drain plug.
I had socket for fill plug so i checked and asked.
Manual says 100k km.
Shifting is a little poor btw 1 2 3 .
So i will buy socket for drain...

Do standard transmissions truly ever fail? I've never seen it happen.

Hi,
Mine have/do.
On my 5th gearbox in 20 years.
Lost 3 in four years.
My present one has lasted over ten years. a Little noise on 1st. Too expensive to replace at the moment.
Cheers,
Iain.

If the oil is at 150k, it’s likely to have wear materials, particles, moisture, etc.

Generally manual transmissions and differentials are considered “bulletproof”. Some of this is likely because they don’t face combustion situations/byproducts, don’t have the shearing and need for providing hydraulic pressure, and so they’re used in a much simpler way. So a relatively simple lubrications approach is sufficient to satisfy the need.

Honda had a reputation in the past for input shaft bearings going bad at under 100K miles especially in the Civics even with 30K mile MTF changes.

prolly not good a long time ago but as noted manuals, my choice are longer lasting + durable except for a possible clutch job!! FWD's with shared driveline + tranny juice need more changes like a motorcycle that uses oil for engine + clutch, its your $$$ + DIY is CHEAP!!!

I have only dealt with class 8 trucks but, yes, they do wear out. First the syncros, from sloppy shifting, then the bearings follow. Gears usually look like new.