Solving manual trans whining sound.

I replaced my 106k 2003 manual 5 speed transmission 4x2 with some off brand 75/90 trans oil. Two months on the gearbox is making a whining sound now. It goes down as engine deacelerates between shifting. I wish I had used OEM equivalent. It starts to whine after driving awhile and the gearbox heats up. What’s my best course of action? I chose Castrol GTX Manual Transmission fluid as it meets OEM specs. $14 qt. Drain and fill, drive awhile, drain and fill, drive awhile, drain and fill? No shifting problems, no drop in mpg. Can’t stand that whine tho. Did I just answer my own question? I’m hesitant to use Sea Foam Trans product. I just want all the old out and fresh in and see if the whine goes away. Gawd, I hope it does.

Fun fact I just read. Only 15% of US sold vehicles now have manual transmissions, while in Europe 80% still have manual transmissions. Must be the roads over there?

 

If the oil was directly responsible for the noise, it wouldn't have taken two months to start. Draining what you have would at the very least be an opportunity to see if there's any metal in it.

 

There were tiny metal fragments in the diff, none in the trans. It may have been less than two months after the fluid change that the whining started. I’m thinking the 1/3 you can’t completely drain out mixed unfavorably with the new off the wall brand. I’ve read that can occur. I’m sorry I can’t remember what brand I bought on this,most likely, first transmission oil change. It was a no name and likely not an OEM equivalent. The Castrol GTX is, in all respects. It specifically states for manual transmissions, GL 5.

 

In a manual transmission you don't leave very much behind when draining, definitely not 1/3.
Have you rechecked the level since you changed the transmission oil?

If there is truly a problem no "mechanic in a can" (Seafoam, etc.) will fix it, save your money.

 

I'm sorry you're experiencing this. I sincerely hope you find a fix.

I think you'd be smart to flush it.

 

There are a lot of GL5 75W90 oils that meet OEM specs and claim GL4 compatibility but are not safe for the brass synchros in the transmission.

Redline MT90 is frequently recommend and is brass safe. There is also an AMSOIL equivalent but I don't know which off the top of my head.

 

it's not the roads that are reason for Europeans driving manual transmissions more. They aren't as lazy as Americans are.

 

Yes, I considered both those brands. $20+ a quart. At $14 a quart with Castrol’s trans fluid specifically stated for manual transmissions, I’m reasonably confident it’s an OEM equivalent. Better than that no name 75/90 for $8.99 that’s in there at the present.
To get out all whatever mixed with the original fluid, I may drain and fill, drain and fill.


Of course I’ll change out the fluid and see if that instantly fixes the whining sound, I’m suggesting it may take doing that 2 or 3 times before the trans has pure OEM type fluid in it.


Thanks for the input.

 

good luck!

 

I have trouble believing that adding fresh 75w90 gear oil (regardless of brand) caused a whine. That is, unless that was the very first oil change in it's 106K life.

If you are cruising along at 40 mph (or so) and it is whining away, what happens to the whine if you put the trans into neutral and let out the clutch and coast along? Does the whine go away?

 

In between shifting 1 to 3 gears, the trans whining goes down between shifts. I’m hoping it’s just a bad mix of original and whatever 75/90 forgettable brand I bought. I don’t want to hear I’ve done permanent damage, gulp.

 

Link to the Castrol GTX manual trans fluid you used? I am not finding anything from Castrol that fits that description. The manual calls for GL4 so if that Castrol stuff is GL5, probably need to replace it promptly.

Hows the fluid level? Do you have enough fluid in the trans? If it's low, it can whine. On Amazon, the MT90 works out to $16/bottle if you buy 4 or they're $19 each. You'll need almost 3 to drain and refill so you can spend $57 and get 3 or spend $64 and have an extra one.

Also, with a manual trans, you don't need to do the drain/fill/repeat thing. It only needs it one time. It's not like an auto trans where you have a bunch of fluid stuck in the torque convertor, lines and cooler that you don't get when you drain. I'd hate for you to spend 2-3x more than you need to buying all that fluid!

 

These packets of wisdom is what makes the forum.

 

Lower in this thread , there is some good info
https://www.tacomaworld.com/threads...on-your-5-speed-transmission-write-up.338836/

 

The mechanic doesn’t think it’s the bearings, thank goodness. Just now got him to change trans and diff with the Castrol GTX. Fingers crossed.

Edit: Unfortunately the whine is still there. Trans mechanic didn’t feel it was any thing of real concern and to just live with it. He doubts using Redline or Amsoil fluid would make any difference.

 

On the GL4 vs GL5 thing, the owner's manual says GL4 or GL5, at least for 2004 and I'm pretty confident '01-04 are the same. Blocker rings don't mesh with anything in steady-state driving so there's nothing to cause a whine. I really doubt the oil had anything to do with it.

My 5-speed whines a bit although I seldom notice. No metal came out and it has good synthetic GL5, so I'm not going to worry about it. Now the rear end when it was losing the carrier bearings, that was shedding flakes of bearing race.

 

The viscosity specifications on

$29 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 are VERY wide range
Also, cheaper brands will usually use low quality viscosity index improvers which shear down quickly (makes the fluid thin within few thousand miles)

Tough to say much on the Castrol transmission fluid without the full product name

I run Castrol Vecton 15W-40 CK-4 in my transmission and transfer case.
Much quieter, no grinding even in 5th gear from slow speed.
None of the additives which corrodes brass synchros

 

Oreilly’s had the most specs. Scroll down to “Applications for Your Vehicle”, then “Show all details’” Their site said it didn’t match my 2003, but Castrol says it does. Anyone tried an additive such as Liqui Moly or one of the many others? I have my doubts about them quieting the whine. Not that expensive, $10.
https://www.oreillyauto.com/detail/...ear-oil-75w-90-1-quart/casp/syntrax7590?pos=8

 

What do you mean?