Anybody have a bottle of this stuff handy? Is the API spec listed on it? Is it GL-4? Or, GL-5?
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Re: GM Axle Lube, P/N 1052271
I don't think the label shows the spec, but as an axle lube it meets the requirement for our axles and tranmissions - Mil-L-2105D, which is essentially the same at a 80W-90 GL-5. It is suitable for vintage manual transmissions and hypoid axles.
With positraction axles one to two 4 oz. bottles of the GM positration additive should also be used.
Duke -
Re: GM Axle Lube, P/N 1052271
Thanks, Duke. Yeah, that's where I'm trying to go with this. Not arguing with you - I appreciate your knowledge. Just trying to understand the difference between GL-4 and GL-5
I always understood that rear ends and trannies both get SAE 90 weight gear oil. Posi rear ends also get an additive. Seems GM still feels that way, and sells this product for it. I understand this.
Now I'm trying to figure out what modern synthetic oil should go into my just rebuilt '62 T10. (Because I need such severe use oil in my T10 that I drive like a little old lady 1500 miles/year.) I'm looking to translate SAE 90 into today's GL-4 and GL-5 API ratings.
So I'm trying to understand the distinction between GL-4 and GL-5 so I can make my own decision. (And, of course, use the better stuff available today thereby improving on Chevrolet engineering.) I have the API specs. As you stated earlier, the API spec tends to GL-4 for transmissions (spiral bevel gears) and GL-5 for rear ends (hypoid gears).
But you advise GL-5 for transmissions because it most closely follows MIL-L-2105D. Your 1963 shop manual specifies MIL-L-2105D. But the shop manual for my '62 T10 does not list the MIL spec. - just plain old SAE 90.
This gets more confusing. The Redline Internet site states that GL-5 is too slippery for transmissions and that the additives in GL-5 are corrosive to the brass or bronze synchronizers in older transmissions. Then the Royal Purple Internet site has their Max Gear covering both GL-4 and GL-5 - one size fits all.
I was trying to come full circle and see if the GM mineral oil was API rated. Maybe that'd point me in the right direction.Comment
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Re: GM Axle Lube, P/N 1052271
Chris -
I have containers of both Sunoco and Valvoline (dino) 80W90 gear lube, and both indicate that they meet both the 2105-D and GL-4/GL-5 specs. Considering the likely duty cycle of your T-10, I wouldn't do any hand-wringing over lubes - just put 80W90 gear lube in it and don't worry about it - the T-10 will probably last longer than you willComment
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Re: GM Axle Lube, P/N 1052271
I've tried to sort out GM's lubricant recommendation for our old four-speeds, but to no avial. I use Redline in some of my cars - MTL (70W-80 GL4) in the five speed manual transmissions of my Mercedes 190 and Cosworth Vega (OE recommendation is ATF for both) and MT-90 (75W-90 GL-4) in the transaxle of my MR2 - OE spec is 75W-90 GL-3 or 4. (GL-3 is currently considered obsolete.)
It's important to remember that modern gear lubricants are specified by BOTH VISCOSITY and GL-SPEC, so you need to be sure that whatever you use meets the spec on both accounts.
I believe the Mil-spec was used by GM because the API GL-specs did not come along until after our cars were built, but everything I have read indicates that Mil-L-2105D and its successors are the same as 80W-90 GL-5. I don't argue with Redlines discussion of GL-5s vis-a-vis their performance in synchromesh transmissions, and that just adds to the dilemma. GL-5s have a higher dose of extreme pressure additives that Redlines claims can be corrosive to brass synchronizers. GL-5s are required and specifically blended for hypoid gears, but they don't sound correct for tranmissions.
I don't have the time, resources, or inclination to run long term gear lubricant tests, so I always make sure to follow manufacturers recommendations. In the case of our vintage four-speeds, I don't think you can go wrong with the GM ...771 porduct. I use it in the transmission and axle of my Corvette along with the additive and also use it (with additive) in the Positraction axle of my Cosworth Vega.
If you want to pursue this further, consider e-amiling Redline with the information on GM's recommendation and see what they say. Their equivalent to the GM lubricant is their 75W-90N/S GL-5 gear oil, which does NOT contain the limited slip additive. Their 75W-90 GL-5 DOES contain the limited slip additive and is suitable for positraction axle use without additional additive. I have heard that it works okay, but have not tried it myself in a positraction axle.
DukeComment
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Re: GM Axle Lube, P/N 1052271
Chris,
Good luck finding 'the truth' on this one.
There are two potential issues w/ using a GL-5 in a manual trannie. Is it 'friendly' to yellow metals (synchros) and does it provide smooth shifting. (now if the shifting were REAL notchy, that too could be detrimental to synchros).
Traditionally a GL-5 IS corrosive to yellow metals over the long haul. However in some (many?) cases, a 'MODERN' GL5 is generally safe for yellow metals. Which OTS GL-5s are and aren't? I have no idea!
GL-4s are essentially required to have significantly lower EP (pressure) additives. THis suggests they may tend to have different degrees of 'slipperiness' as I like to call it from a GL-5. Since a transmission gear tooth has almost no slipping action on it's teeth there is no real need for a full GL-5 in that regard.
GL-5s in transmissions are further complicated by the near omnipresence of limited slip additives in most modern GL-5s - the presence of a limited slip additive in a transmission will also likely further affect it's friction and also have an impact on smooth shifting. Some GL-5s (Presumably the GM ...271) do not include the limited slip additive.
GM does not seem interested in going thru the effort or cost to have their gear lubricant API certified. Even if it were, it would not likely result in additional 'external' sales. After-all GL-5s are as common as they come.
I also doubt they have much interest in keeping up w/ providing an optimal lubricant solution for a vintage 30 or 40 year old transmission. THey happen to offer something that works OK across a broad spectrum of gear boxes and seem satisfied with that as it is.
Let's forget for a moment about those using ATFs and Synchromeshes or other proprietary transmission lubes, automakers tend to fall into 3 categories for transmission lubes. They either spec a GL-4 only, a GL-4 'OR' a GL-5, or a GL-5 specifically. The ones spec'ing GL-4 always supply GL-4 to their dealership network and perhaps even for sale retail. Let's be clear that GL-4s are not that common, so those makers know they must go thru a special effort to ensure GL-4 is distributed. The ones suggesting 'either' a GL-4 'or' GL-5 are merely fence sitters. Those listing just GL-5 (like GM) are doing themselves a favor. Some oil companies don't bother to make a GL-4 and strategic business relationships do exist (No, GM does not make it's own oil). They can choose a supplier for their GL-5 'label' from anywhere but only 2 or 3 for a GL-4. They don't have to have two(2) part #s in their system (can't abandon GL-5!) or stocked on their shelves or contained in barrels. They also don't have the liability that some idiot may put a GL-4 in a differential.
As for those lubricants that claim to be both a GL-4 and GL-5 or 'combo' as I call them - I'm a little ambivalent about them. My opinion is that you are getting a compromise. You are essentially getting a GL-5 that guarantees it is not corrosive to yellow metals. Beyond that, if it's nice and slippery for a hypoid gear - it 'may' also not be well suited for smooth synchro operation. As far as I'm concerned, the jury is out on 'combo' lubes as I've not taken the time to experiment much with them in transmissions.
In my own experience on manual transmissions from teh 60s and 70 from N. America, Asia and Europe, a pure GL-4 provides the smoothest shifting. I've compared that to a GL-5 75W-90 (synthetic) that happened to include limited slip additive and the shifting has always been notably 'notchier'.
A GL-5 will work 'OK' in a manual trannie. Even if it is corrosive to the yellow metals - it will not likely be an issue for a very very long time. It may have an impact on smooth or notchy shifting but this is subjective and does vary somewhat between different makes of trannies. Muncies do tend to be a little more tolerant of GL-5s w/ respect to decent shifting. (in fact they are just about tolerant of anything ) This tolerance to a GL-5 and still producing decent shifting is probably why you will not find a lot of strong opinions for a GL-4 within vintage GM circles.
If you contact a company like say Redline - you will find that they will rarely if ever deviate from the manufacturers original recomendations. In the case of a vintage Corvette, they will simply recomend their GL-5 product, which is 75W-90NS. However their MT90 product is the one I personally prefer in most any 4 speed or 5 speed regardless of whether the maker spec'd a GL-4 or GL-5 (but not a motor oil, ATF or proprietary fluid).
When it comes to gear lubes my philosophy is 'less is more' - I rarely change these fluids and I want a good oil that is specific to my application and does not contain anything I don't want and precisely everything I do want. But if I were constantly changing these lubes I might find a general or less specific lube to be preferrable (sorta like a GM dealership?) such as a GL-5 or GL-4/5. Most modern GL-5s that include limited slip additives (and most do) work just fine in most any limited slip diffy or open axles.
Now if you want to be 'real' precise you can use a GL-5 that does not include it (like the GM 271) and then add a bottle of GM additive. If you still get 'chatter' then add incremental portions from a 2nd bottle until you sneak up on a chatter free diffy. Generally somewhere between 1 and 2 bottles is about right.
Finally I'll add that, while in general I'm very ambivalent about synthetic oils, a good case can be made for them in gear lubes if for no other reason, the infrequency of fluid changes.
The companies offering a pure GL-4 in either conventional or synthetic includes:
Redline (synth)
Amsoil (synth)
Sta-Lube (conventional)
Pennzoil/Quakerstate (both conv & synth but only in bulk very HTF, the synth is VERY expensive)
Chevron (conventional, probably bulk & HTF)
Valvoline (conventional, probaby bulk & HTF)
All of these are multi-weight lubricants. There are simply no straight weight GL4s available. There are few if any straight weight GL5s left for that matter. But a modern multi-weight is really a great solution particularly on a cold morning. I believe all the synthetic GL-4 specific lubes available are Group IV PAO synthetics. Motor oils and GL-5s often are Group III refined synthetics and some believe a Group IV PAO is better. All I know is that the argument is mute w/ respect to GL-4s.
Some dealerships (non-GM) have separate GL-4 (from GL-5) on hand but usually in large containers for service purposes. A few (Nissan? VW?) may also sell a GL-4 in smaller containers to consumers but don't hold your breath.
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Now the questions I have are:
1) Who bottles GM's 271 'GL-5'-like product?
2) And what's the difference between these two GM manual transmission fluids: 12346190 and 12345349? Are they both 'Synchromeshes' one being the Castrol synthetic and the other being the Havoline/Pennzoil/Quaker conventional respectively?Comment
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