MasterPro GL 4 Gear Oil

[delta31]

I stopped by an Oriellys store yesterday and notice a gallon jug of MasterPro GL-4 SAE 140 Gear Oil.
I have read alot of about the manual transmission oils and the need to use a GL 4 where there are brass parts.
Has anyone hear used this product in thier M37 transmission?

I have looked into Redline, Amsoil and Lucas. The price was not the problem. It was availability and shipping time.

Thanks

[sturmtyger380]

I use the - Lucas Synthetic 50 WT Transmission Oil.

I had Oriellys order it to come to their store. Took maybe two days. But that was before the supply chain crisis.

[ez8]

I assume you're refering to this product:
https://www.oreillyauto.com/detail/c/ma ... mp03/80040

I have never used it, but I think I might try it out in my transmission and transfer case. I have been using Redline Synthetic, but since I have an original truck with original seals the synthetic stuff finds its way out pretty easily.

[Murf]

Todays crappiest lubes are way better than those of the 50s & 60s. Regardless of which brand you get it will be better than what was originally available (and worked).
Yes. Leaking is the new problem.

[John Mc]

I'm no lube guru, but isn't an SAE 140 way to high a viscosity for the stock transmission ans transfer case?

An SAE 50 oil is the equivalent viscosity to the 90 weight gear oil recommended in the manual.

[ez8]

I'm no lube guru, but isn't an SAE 140 way to high a viscosity for the stock transmission ans transfer case?

An SAE 50 oil is the equivalent viscosity to the 90 weight gear oil recommended in the manual.

The problem with SAE 50 is I have never been able to find it in a container that isn't at least a 5 gallon bucket and is a conventional oil.
There's quite a few synthetics out there (like Amsoil, Mobil Delvac, etc.) but if you have a lead on a conventional one that comes in 1-2 gallon containers I'm interested.

[John Mc]

No leads on a conventional. I use synthetic in my truck.

[ashyers]

delta31,
I'm using it in my winch .

For the transmission it's worth the wait for Redline MT90. It improves the shifting greatly and I've had no leakage issue if the transmission is not overfilled. If overfilled it will pump a bit out the input shaft as it finds its level. I do not fill to the lower lip of the fill screw! At some point there was a bulletin on this, but I don't have a copy. One of the screws in the side cover plate is pulled to determine the level. I order from Summit, they're fast.

Andy

[John Mc]

... I've had no leakage issue if the transmission is not overfilled. If overfilled it will pump a bit out the input shaft as it finds its level. I do not fill to the lower lip of the fill screw! At some point there was a bulletin on this, but I don't have a copy. One of the screws in the side cover plate is pulled to determine the level.

The procedure for checking the transmission lube level is spelled out in note 5 of the Lube Order found in TM 9-8030 (page 62 in my copy). It does describe using the cap screw in the upper rear side of the right hand power take off cover as the fill level indicator.

M37 Transmission lube.pdf

(111.82 KiB) Downloaded 138 times

[ashyers]

There you go!

[John Mc]

I see a lot of comments here ans elsewhere that synthetic lubes cause leaking. It appears there was some truth to this in the early days of synthetic lubes, as they could leach something out of the seals affecting their performance. The specs for modern synthetic lubes are more seal friendly, and include conditioners to prevent this from happening.

I suspect that if a switch to a modern, quality, synthetic lube caused a leak, that there were other issues (over filling, or your seals were relying on a layer of crud to help seal things up, which the new lube may have loosened up or removed). Again, I am far from a lube guru, but I've tried to research this, asked others with a lot more experience than I, and exchanged emails with a couple of lube manufacturers.

My transmission leaked when I first switched to Amsoil SAE 50 Long-Life Synthetic Transmission Oil. \here was a bolt or two that needed some sealant on it, but the main culprit was that I had overfilled the transmission (as Andy noted). My problem was made worse by the fact that when I noticed the leak, I got concerned and added a bit more. THe leaking seems to have stopped, now that I let the level drop.

A question for those with more experience: the manual notes that when replacing the cap screw, we should discard the lock washer and use a copper or brass flat washer. Should that be replaced with a new washer each time it is filled? Do people find that Locktite or something similar is needed to prevent the cap screw from vibrating loose since it has no lock washer now?

[ashyers]

John Mc,
I like copper washers because I can anneal and re-use them. I put some Loctite PST on the threads too.

Andy

[just me]

D-A lubricants sells GL-4 in quarts to barrels. 80W-90.
Go to penngrade1.com and click on gear lubricants.

[NAM VET]

a year or so ago, Charles T suggested I think on this forum that he feels this Amsoil product is superior for our transmissions. So I drained and refilled mine, which has always shifted like a dream. I have a very slight leak, and filled mine to the bottom of the fill plug threads, which may be the issue with my very slow drip. To avoid having to crawl under my truck to check the location of the referenced bolt Vs the fill plug, anyone guess how much lower the bolt thread hole is? This product. I presume of course is safe for our transmission brass parts.

Hal

[John Mc]

I have not actually measured the difference, but someone else once told me they just reach inside the fill plug with their little finger and see if they can touch the fluid. If they can, they figure it's OK. Not very scientific, I know. Since I can't fit my little finger all the way in, I'm just guessing that a solid tough on the fluid with my finger amounts to about 3/4" below the fill plug? At any rate, that's where I am now, and my transmission drips have stopped. I put a fresh piece of cardboard under it and there are marks from two drops on it after several drives and then a couple months of mostly sitting.

I had thought of making some sort of little dipstick with an appropriate bend in it that I could stick in the fill plug sometime when I know I've got it filled to the correct level using the described procedure, so I could get an actual measurement. I've just never gotten around to it.