GL4 and GL5 Oil - Transmission Lubrication Oils Explained

I discuss some of the new oils today for manual transmissions and take apart a Muncie 4 speed that welded up. There has been a great deal of misinformation about GL-5 based oils corroding synchronizer rings. I've never seen this happen in 1000's of tranmissions I've serviced. We have seen more GL-4 based oils come to the market within the past 3 years, but prior to that everyone was OK using GL-5 oil for the past 20 to 30 years. The new GL-4 oils are a plus because we now have better formulated oils for our muscle car transmissions.
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disclaimer:
The content of this video is available for informational and educational purposes only. It is not intended to be a substitute for the professional advice of a mechanic who has personally inspected your vehicle, nor does it create a relationship of any kind between GearBoxVideo (Paul Cangialosi) and you. Every situation may be different, and GearBoxVideo does not make any warranties, whether express or implied, as to the accuracy, fitness, or applicability of the information or automotive parts portrayed in this video to any project and makes no guarantee of results. GearBoxVideo and any sponsors or manufacturers of parts that may appear in this video or any of the channel's content will not be liable for any damages related to personal injury, property damage or loss of any kind that may result from the use or reliance on this video and/or any automotive parts represented in this video. You are using the information and automotive parts portrayed in this video solely at your own risk.

[EdWatts]

I'm a mechanical engineer, an ASE-certified master technician, and I have spent many years in the aerospace industry as well as owning and operating an auto-repair facility; and I have to say that you, sir, have made a really good video!

Thank you for your time and effort.

[inverseuniverse]

I hope that there are still many transmission repair techs that can do this you are a dying breed .

[jemcnair]

If you close your eyes you can hear Harvey Keitel give a wonderful lesson on transmissions and oils.

[drigney]

It's fun to watch the few videos done by knowledgeable people who are passionate about their work. This guy is clearly one of those people. Watching this makes me wish I had transmission problems just so I could have him fix it! Very well done Paul. Thank you taking the time to make this video.

[tedg]

What a pro this guy is. Love seeing masters of their craft showing the world what they do.

[tigerseye]

Hi Paul. I've been a DIY shade tree mech all my life ( 72 ) . When I watch your channel I know I'm getting straight and honest info. Your experience and skills run deep. You are much appreciated by myself and others. Thanks for sharing.

[GearBoxVideo]

PLEASE READ:
Wow this video is getting a great deal of hits lately. I'm noticing the same questions asked over and over so please take the time to read other comments I have responded to. First off this transmission locked up on a dyno because they forgot to put oil in it. In regards to what OIL I think is best for your transmission... There will always be debates from fans of various oil brands as to what they think works best. If it works best for you and you have exhibited better performance, less wear and are happy with the result, then that oil is best for you. With so many transmissions with different types of clearances and synchro types, understand that what may work great for you may not for someone else.
OIL TEMPERATURE COMMENTS: There are some that will argue that unless I did these tests with the oils at operating temperature that they are meaningless. This is not true. Manual transmission oil when cold will greatly effect how the transmission will shift UNTIL it warms up. However that is not even the point of the comparison. The point of the comparison was to show how the different advertised grades of the oils compare when cold. In the future I will probably do a test with oils at an average operating temperature.
THANK YOU ... for taking the time to watch my videos and subscribe.

[lizard]

You open that case and throw parts around like, "La, La, La,La" "I've done this 10, 000 times." I'd be taking more pictures than I would on a one month vacation cruise...lol!

[frenchenstein]

Good to see a transmission guy on YouTube that knows what he's doing. I rebuild manual transmissions too. Great video.

[georgedennison]

My Gawd, I haven't looked inside a Muncie in 30, no 40 years! I love it... I about 15, when the guy who owned the Esso station taught me how to rebuild transmissions. This was '68, so it was 3 & 4 speeds everywhere.

The funny thing about Gary, the station owner was you would think he'd never be able to get a hand inside a Muncie, , let a lone rebuild one. The first strong memory I had during the vid, was the pain involved, the cuts and nicks, the smashed fingertips. LOL

Gary was about 6'2-6'3" and had to weigh 300-350, easy..probably more, it was a long time ago. But that guy could tear apart and rebuild a transmission like he was playing piano, it was amazing. He did everything with his fingers. He was strong enough in his hands, and his fingers were long enough, it looked like he was washing his hands in a finger bowl, then bang, out pops the cluster, or "You can put the side cover back on, it's done.", and you're still cleanin' the damn side cover!

Thanks, I haven't thought of that in 20-30 years easy, a lot of that I'd forgot since I saw it happen. Thanks, again.

Oh, that Brad Pitt oil looked like the good ol' green, stinky tranny lube I recall. If it has a tendency to hang a bit more, that may be a big asset in heavy load situations, keep a better layer on the gears, themselves.

[JCKLFUL]

“We’re gunna have to make a video on this one” hell yeah!! So glad to see some new stuff man, it looks super good!! Great editing too, your stuff is looking so professional!

[paulbakovic]

Finally a man that knows his transmissions and knows how to teach, explain and show how to do it.

[Bathy]

Hi from Australia, Truck mechanic here, Years ago my son had a Holden LD Astra, basically a re-badged N13 Nissan Pulsar,
he decded to freshen up the gearbox with new oil, went down the local parts store, got the oil they recommended.


1 month later this box was stuffed, grinding every gear, luckily he had another box, so he decided to just swap the box, instead of re-building it.
Anyways, i got home from work midway through his swap, and noticed a drain container full of black oil, "ohhhh, changing the engine oil too, i see" i commented,
he replied, "nope, that's the old gearbox oil" I knew straight away exactly what had happened, asked for the old bottle of oil he used in it and the new oil he was going to put in his 2nd box,
yep, both the same, both GL5. A quick search in the manual showed nissan specifies GL4, he went straight back and swapped the GL5 for some GL4,
the parts store accepted no responsibilty for their error, they (incorrectly) argued that GL5 just supercedes GL4, long story short, we don't use that part store anymore.
that 2nd box with the GL4 was still going strong years later.


Another thing I've noticed in all my years twisting spanners, is the effect synthetic oils can have on old gearboxes.
mainly if it's an old box designed back when only mineral oils were available, with most likely, larger tolerances,
they tend to shift better with mineral oils and become notchy with the fancy synthetics.
This is really noticable as well on the Eaton-Fuller road ranger non-synchro boxes too,
factory specfies, DD50(sae 50) engine oil, shifts nice, put in a synthetic gear oil, notchy.


new boxes on the other hand, designed with tighter tolerances tend to work better with the new synthetics.
even with making sure the viscosity is as the manufacturer specifies, the synthethics just don't seem to shift right in old boxes,
just what i've noticed anyways. Cheers.

[paulmullins]

The master at work. The info this well experienced man has to offer is priceless

[Roy_Godiksen]

I found both the gearbox and the oil test very fascinating.

[jdickson]

Got here looking for comments about transmission oil now im hooked. Im amazed that gearbox is repairable.

[ON]

Paul, a good take on the GL4/5 saga. Thanks for taking the time to publish these videos.

[datsuntoyy]

"looks good but junk because they were running in dirty oil". I like the honesty. too many would just say, "it'll make it past my waranty, that's all I care about" As a former mechanic myself, I know it's really hard to find good ones anymore. Kudos.

[xblinkusedfinchx]

Your videos are the best gearbox videos on the internet!! You rock!

[boldlionpro]

This video was perfect. Been amazed at how a transmission actually works and when I saw you take it apart and then the soft metal synchros fell out, I was blown away at how such a machine is engineered, it’s amazing! Thanks for your research, your valued opinions and work in this field-respects to you Sir!