GL4 or GL5 for manual transmission?

[Elkins45]

I recently bought a 2009 Scion xB with a manual transmission. The owner’s manual specifies GL4 or GL5 as a replacement fluid, but I’ve heard people say that GL5 is harmful to certain parts in manual transmissions. Surely Toyota wouldn’t tell people they can use GL5 fluid if it was going to damage their transmission? Right? Now I’m worried that my recent fluid change might do more harm than good.

 

[Kira]

Yeah, "yellow metal alloys" (brass/bronze bushings) must be absent in that transmission but I do not know.

 

[ammolab]

A lot of GL5 fluids state that they are NOT harmful to brass/bronze alloys. Lubricants change, things improve.
Check into the GL5 that you used. The info should be on the makers site.

 

[aquariuscsm]

If your transmission allows the use of GL-5 lubes, I wonder if a dedicated manual tranny lube will still provide better shiftability?

 

[tcp71]

There a so many really good GL-4 lubes out there. It is so easy to change MT fluid, just swap it if you’re worried. That being said, Toyota allows it , so it shouldn’t be a worry.

 

[slacktide_bitog]

The only 75w90 suitable for manual transmissions that you'll find on the shelf of a US store is Liqui Moly 20012 at Napa. Search LM20012 on Napa's site.

This is the hardest thing about having a non-Honda manual transmission. Hondas can use the Valvoline or Pennzoil Synchromesh you can actually find, but they're too thin for anything else being thinner than 75w90. Hondas can even use motor oil

Also, one more piece of advice: DO NOT buy the UltraLub/Ultra1plus GL4 on Amazon! Check out the VOA I had done on it

There a so many really good GL-4 lubes out there. It is so easy to change MT fluid, just swap it if you’re worried. That being said, Toyota allows it , so it shouldn’t be a worry.

Canada has more options than the US. For example, you can actually get the Pennzoil Platinum Gear 75w90 that doesn't seem to be available anywhere in the US. Napa sells it in Canada, but not the US.

 

[Mainia]

75W90NS GL-5 Gear Oil

Designed for transmissions and transaxles - helps to slow synchros for easier shifting across a broad temperature range

www.redlineoil.com

 

[slacktide_bitog]

75W90NS GL-5 Gear Oil

Designed for transmissions and transaxles - helps to slow synchros for easier shifting across a broad temperature range

www.redlineoil.com

Redline's MT-90 would be more suitable for the OP's Scion.

 

[RyanY]

The only 75w90 suitable for manual transmissions that you'll find on the shelf of a US store is Liqui Moly 20012 at Napa. Search LM20012 on Napa's site.

This is the hardest thing about having a non-Honda manual transmission. Hondas can use the Valvoline or Pennzoil Synchromesh you can actually find, but they're too thin for anything else being thinner than 75w90. Hondas can even use motor oil

Also, one more piece of advice: DO NOT buy the UltraLub/Ultra1plus GL4 on Amazon! Check out the VOA I had done on it



Canada has more options than the US. For example, you can actually get the Pennzoil Platinum Gear 75w90 that doesn't seem to be available anywhere in the US. Napa sells it in Canada, but not the US.

I plan to change MT oil in a Toyota Matrix in the near future. How does the LiquiMoly product compare to Red Line MT-90? Or will both perform the same in cars that won't be driven aggressively?

 

[skyactiv]

Long time manual trnmasssion owner here. I have used GL5 once a manual gear box. Never again.
GL5 gear oils are too slippery and your shifting will suck. I don't care if Toyota says you can use it. The MT1 spec on the bottle means nothing either.
It will feel more slippery which you may like but don't expect to change gears without the very occasional crunch.

If you have money to burn, get the Miata owners favorite. It is a true PAO German fluid. Read some reviews and why it gets a 5/5 by hundreds. I put in a VW GTI I once owned.

https://www.amazon.com/Genuine-Ford-XT-M5-QS-Synthetic-Transmission/dp/B000NUES82

 

[Elkins45]

In looking at fluids I've seen "synchromesh" manual transmission fluid listed. What is that?

 

[ceecbtg]

Advice: Don't use GL5 if you don't need it. If you don't know if you need it don't use GL5.

Also, one more piece of advice: DO NOT buy the UltraLub/Ultra1plus GL4 on Amazon! Check out the VOA I had done on it

Well about Ultralub GL4 it's not bad or terrible. It's true GL4 formulation from downgraded GL5 with alternative multifunctional phosphorus. It's very different to classic additives from other. Amsoil and Motul use it too. I won't enter if this alternative additive is better or worse.

Redline's MT-90 would be more suitable for the OP's Scion.

+1 If very cold weather I'll go to MT-85 if spec allows it.

 

[Scuder]

In looking at fluids I've seen "synchromesh" manual transmission fluid listed. What is that?

It's a GM spec fluid. The Pennzoil brand is about an SAE 80 at 100°C, and claims to be friendly to yellow metals. A friend of mine is using it in the A-833 four speed in his Cuda 440. He loves it.

 

[sk_pete]

A lot of GL5 fluids state that they are NOT harmful to brass/bronze alloys. Lubricants change, things improve.
Check into the GL5 that you used. The info should be on the makers site.

Today's oils are often "gl4/5". That should be safe.

 

[MolaKule]

Check out the list of Dedicated MT fluids here according to Grade Range and actual 100C viscosities:

 

[Oliveoil2]

Thanks MolaKule, great info. I just use the manufacturer product. Honda, Toyota, BMW, they all work well and are readily available. I usually go 60-80k between drain and fill.

 

[930.engineering]

Does this car actually require a 75W-90? What does the manual say?

 

[Elkins45]

Does this car actually require a 75W-90? What does the manual say?

Here’s a screen grab from the manual:

 

[Elkins45]

I understand anecdotes are useless but I’m pretty sure I used an off the shelf 75w-90 gear oil when I changed the fluid in my 07 Corolla and I know it went at least 180k miles without any issues before I sold it. I’m tempted to run it at least a few thousand miles (unless it starts acting up) and use it as a “flush” because I’m fairly sure the oil hadn’t been changed in a long time (if ever) when I bought it.

I see Carquest sells a 90w GL-4 gear oil. That might be a good summer fill

 

[930.engineering]

Thanks. I still do agree with those saying to prefer a GL-4 only fluid.
The Scion xB has a transverse mounted engine? If so its transmission
very most probably lacks hypoid gears and won't benefit from a GL-5.
Redline MT-90 is certainly a good choice, perhaps also MT-85, which
will likely provide an even better shifting experience. It certainly will do
when cold. That said, 2.6 quarts seems plenty for this kind of car.