GL4, Still best to use and where to get?

[TDLightweight]

Hi Everyone,

Now that Olive's rebuilt Transmission is installed, I have to reopen this old debate. This subject has been hashed about a few times and my feeling is that there are two separate camps. Those that have used GL5 and have not had a problem and those like me who are more cautious.

The legend is that additives in modern day GL5 transmission oil will attack the bronze pieces in series's truck transmission.

In my case I have drained the oil three times on my transmission since its first rebuild and both times saw a golden metallic sheen floating on the used oil. Now the reason that my transmission failed was due to a collapsed layshaft rear bearing so it is possible that a lot of the contamination was from this bearing self destructing over time but I doubt it. For the record I was using GL5.

Initially I though the metal showing up was from the transmission breaking in but the second time I dropped the oil there was the same sheen which got me thinking. So I can say that I am now in the GL4 only camp.

Let the debate begin....

Having decided that I would like to try GL4. I have discovered that it is not easy to find as I had hoped. I will probably go with Redline as they still offer a GL4 oil but would like to know if someone else has found a good source. The guys at Lordco gave me blank stare.

[red90]

Redline should be a good choice. Beyond the GL4 thing, a transmission fluid has better friction characteristics for the synchros than a pure gear oil.

You would not see the dissolved copper as it is dissolved. You would need to do an oil analysis or look at the synchros. The dead bearing was most likely the source of the visible metal.

[rezdiver]

I have been looking into this for some time, since GL5 is now more popular the GL4 has been rebranded as synchromesh and sells for more than double the price it used to be.

I found if you go to some mechanic shops and oil change places, they have a large amount of the old GL4 they dont use anymore, or dont use as much. they usually give you a good deal if you ask nicely to buy a 5 gallon pail of it..

canadian tire has a gearoil that they rate GL4 and the MIL spec number mathches GL4 but there is also a label on it saying it meets GL5. i am waiting to hear back from shell canada as to the composition. shell suppies the motomaster brand for this product.

[red90]

I find it hard to worry about the cost. Redline is around $10 a liter and there should be no reason to change the gearbox oil for years unless you have a leak.

[Greg S]

Here it is again, as written on the Van Isle Website:

GL4 gear oil

I have searched common sources for GL4 oil and it didn't seem available without buying some fancy "Racing" or "Classic Car" mixture. But if you keep digging, you'll strike oil, and strike oil I did!

GL4 is the standard oil for use in high pressure, mid temperature operations (gear boxes, differentials), GL5 is for the same application as GL4 but with additives to make it acceptable in limited slip differentials BUT it is not compatible with soft metals in some transmissions and differentials, soft metals meaning the brass or bronze bushings and spacers like those found in old Series Land Rovers.

GL4 oil is very hard to find now as the GL5 is taking over. To buy some good old-fashioned GL4, modernized for other virtues, visit your nearest Chevron commercial supplier, aka Bulk Plant. Ask for Chevron Delo ESI Gear Lube 80-90. I don't know if it is available in quart (or liter) sizes but it is available in 20 liter (5 US gallon) size. It is about 2/3 the price of synthetics according to my source. It has a very long usable life and will not attack the soft metals due to its chemistry. It is a Potassium Boric chemistry (which is good despite what some Blogs might say). Most oils use Sulphur Phosphorus chemistry, and this, mixed with humidity in the air in the gearcase makes suphuric acid that attacks the soft metals.

I am lead to understand that Volvo trucks recommend the use of this gear lube as does Eaton Transmission. I haven't checked out this tid-bit though.

In a nut shell, that's it.

[TDLightweight]

Thanks Greg,

I will either go with Redline MT90 or with what you have recommended via the Chevron route..

I found this great link on GL4 Vs. GL5 which explains things pretty well although it does not help too much with locating Cheap GL4 oil in Canada.

http://www.ratwell.com/technical/GearOil.html

[TDLightweight]

That is great info Greg in a nice summary . I will hunt around tomorrow on the phone and see if can locate some of the Chevron stuff. Does anyone want to go in half an half? I still might go MT90 as well.

Here is an interesting link regarding GL4 vs. GL5

http://www.ratwell.com/technical/GearOil.html

[Greg S]

Good VW biased oil info. I've added that as a link from my GL4 oil information.

http://www.vanislelandrovernetwork.com/ ... l#article6

[seriesIIa]

I've spoken with technical reps from Chevron and Petro Canada this week. They both say to stay away from GL-5 lubricants in vehicles that have synchros or where the manual specifies a GL-4. Same old reasons we've all heard about. The Chevron rep does confirm that their Delo gear lube is non-corrosive and will not harm yellow metals, but stops short of recommending it. In short, if it is dual or triple rated, it is not a GL-4. According to the reps, any additional reference to gl-3,4 on a GL-5 product sheet is for industrial gear boxes that can cope with the higher EP levels in a GL-5 lubricant.

CRC makes a product called Sta-Lube that is strictly GL-4. Available at Napa in the states.