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Thread: Wethead Final Drive Lubricant Specification

  1. #16
    You should know that GL-3 and BMW's G3 are two different things. "GL" is an API rating. GL-3 is pretty much an obsolete gear oil. Most everything on the road calls for GL-4 or GL-5.

    "G3" is a BMW name for their current gear oil. They've offered G1, G2, G3, G4 & G5. From what I've been able to find all the current BMW Hypoid oils carry an API rating of GL-4 or GL-5. GL-4 is usually for transmissions and GL-5 is for differentials. They have different additive packages. Some have additives for limited slip differentials in cars but it's not an issue in vehicles without limited slip. (or motorcycles)

    The only question is viscosity. BMW's G3 (and what the manual on my '20 RT calls for) is 70W80. The trend of going to thinner lubricants is for fuel economy. If they spec'd thinner lubricant in their automotive line, it would follow that they are condensing part numbers and just using their "G3 70W80" across the board in current vehicles.

    I can't see any reason a base viscosity of 75 in GL-5 vs 70 in BMW's G3 would have any adverse effect. It is only going to matter when extremely cold and the difference is negligible.

  2. #17
    Quote Originally Posted by danm View Post

    I can't see any reason a base viscosity of 75 in GL-5 vs 70 in BMW's G3 would have any adverse effect. It is only going to matter when extremely cold and the difference is negligible.
    I would be curious as to what bearings they are now using, and whether they are sealed with grease or lubricated by the gear oil. I know that in the Oilhead generation the bearings were gear oil lubricated and were specified as a C5 extra-clearance bearing to ensure that the gear oil could adequately flow in between the balls and races, and that using high viscosity gear oil xxW140 gear oil contributed to final drive failures.
    Last edited by PGlaves; 08-08-2020 at 03:15 AM.
    Paul Glaves - "Big Bend", Texas U.S.A
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  3. #18
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    G3 for 50 bucks a bottle or the bottle Reece showed which is what I have for 12 bucks.

    I also changed my final drive oil at every oil change and since she was new, I used a 4000 miles interval. Now that shes "broken-in", I'm following the 6000 miles interval for engine and final drive oil.
    2015 GSA

  4. #19
    Registered User stooie's Avatar
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    Quote Originally Posted by danm View Post
    You should know that GL-3 and BMW's G3 are two different things. "GL" is an API rating. GL-3 is pretty much an obsolete gear oil. Most everything on the road calls for GL-4 or GL-5.

    "G3" is a BMW name for their current gear oil. They've offered G1, G2, G3, G4 & G5. From what I've been able to find all the current BMW Hypoid oils carry an API rating of GL-4 or GL-5. GL-4 is usually for transmissions and GL-5 is for differentials. They have different additive packages. Some have additives for limited slip differentials in cars but it's not an issue in vehicles without limited slip. (or motorcycles)
    DanM: Yup; I sussed that out. BMW doesn't do us any favors by not being a little more open in lube specifications. As I understand it, there is a big difference in the additive packages in GL-4 and GL-5. One has hypoid extreme pressure additives (chlorine or sulfur based) which can corrode/erode bronze/copper parts in some auto limited slip diffs and transmissions. The G3 specification really doesn't tell us much.

    In general, OEMs will specify a generic lube spec, i.e., API SL, GL-4, or whatever. When they miss on their design and need a really special lube to cover up for their design deficiency, they go to some obscure or proprietary spec. (Ask me how I know; I worked for a helicopter OEM.)

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  5. #20
    Registered User stooie's Avatar
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    Status Report

    Thanks to all who responded! Here's what I've found so far:

    1. The owner’s manual for my 2018 RT makes no reference to a specified final drive fluid.

    2. The June 2020 update to the BMW DVD Service Manual specifies the following for the R1200RT:

    Gear oil (Hypoid Axle Oil G3)

    There is no mention I can find of a viscosity or API rating for G3 oil.

    GetBMWParts.com (a BMW auto parts site) has G3 for $46.10 for a 500-ml jug.

    3. My Haynes manual, published in 2016, specifies Castrol SAF-XO.

    Bimmerworld.com (another BMW auto parts site) has BMW branded C-SAF-XO labeled as Synthetic, 70W-90, GL-5. It’s $20.16 for a 1-liter jug.

    I leave it to you to draw your own conclusions about the reason for the change from SAF-XO to G3. Technical issue? Commonality with their automobile specs? Profit margin?

    Enjoy the ride!
    Bob Stewart
    Salem, OR

    2018 RT

  6. #21
    Page 190 of the '20 RT owners manual says: Rear axle differential oil SAE 70W-80 / hypoid axle G3
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  7. #22
    Registered User GTRider's Avatar
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    Quote Originally Posted by stooie View Post
    Thanks to all who responded! Here's what I've found so far:

    1. The owner’s manual for my 2018 RT makes no reference to a specified final drive fluid.

    2. The June 2020 update to the BMW DVD Service Manual specifies the following for the R1200RT:

    Gear oil (Hypoid Axle Oil G3)

    There is no mention I can find of a viscosity or API rating for G3 oil.

    GetBMWParts.com (a BMW auto parts site) has G3 for $46.10 for a 500-ml jug.

    3. My Haynes manual, published in 2016, specifies Castrol SAF-XO.

    Bimmerworld.com (another BMW auto parts site) has BMW branded C-SAF-XO labeled as Synthetic, 70W-90, GL-5. It’s $20.16 for a 1-liter jug.

    I leave it to you to draw your own conclusions about the reason for the change from SAF-XO to G3. Technical issue? Commonality with their automobile specs? Profit margin?

    Enjoy the ride!
    That last one seems close, especially at $46 per half-liter. If BMW is specifying a specific lubricant in order to maintain warranty coverage, then I’d wonder if they need to supply that gratis under Magnuson-Moss. And if there are no specifics available on “G3”, like viscosity, lube classification, required additives in the formulation, etc then the consumer is unable to reliably source a non-BMW lubricant. And if you use a non-approved lubricant and have a final drive failure your warranty coverage gets called into question. Catch-22 in real life...

    Best,
    DeVern
    DGerber
    1983 R80ST — 1984 R80 G/S-PD — 2004 K1200GT w/Hannigan S/C — 2010 K1300GT — 2018 R1200GS
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  8. #23
    Registered User stooie's Avatar
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    Quote Originally Posted by danm View Post
    Page 190 of the '20 RT owners manual says: Rear axle differential oil SAE 70W-80 / hypoid axle G3
    Good for BMW for adding it to the '20 manual. No such line exists in my '18 manual.
    Bob Stewart
    Salem, OR

    2018 RT

  9. #24
    I may be wrong so if somebody actually knows for sure please correct me. But it looks to me like G3 is a designation for automatic transmission fluid with Dexron III G specification. This would seem to be a very light viscosity.

    See: https://www.lubricants.total.com/bus...passenger-cars

    Scroll down to "Automatic Transmission Fluids with Dexron III G specification"

    I may be misreading this but all other mentions of G3 Google found were BMW or Mini specific.

    I did find some "comment" style opinions saying that G3 was the same as 75W90 GL-5 but I didn't find any reliable source saying this.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
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  10. #25
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    Quote Originally Posted by PGlaves View Post
    I may be wrong so if somebody actually knows for sure please correct me. But it looks to me like G3 is a designation for automatic transmission fluid with Dexron III G specification. This would seem to be a very light viscosity.

    See: https://www.lubricants.total.com/bus...passenger-cars

    Scroll down to "Automatic Transmission Fluids with Dexron III G specification"

    I may be misreading this but all other mentions of G3 Google found were BMW or Mini specific.

    I did find some "comment" style opinions saying that G3 was the same as 75W90 GL-5 but I didn't find any reliable source saying this.
    As I have used quite a bit of this amazingly fragrant bit of modern lubricants,
    I saw the following-
    Quote Originally Posted by danm View Post
    You should know that GL-3 and BMW's G3 are two different things. "GL" is an API rating. GL-3 is pretty much an obsolete gear oil. Most everything on the road calls for GL-4 or GL-5.

    "G3" is a BMW name for their current gear oil. They've offered G1, G2, G3, G4 & G5. From what I've been able to find all the current BMW Hypoid oils carry an API rating of GL-4 or GL-5. GL-4 is usually for transmissions and GL-5 is for differentials. They have different additive packages. Some have additives for limited slip differentials in cars but it's not an issue in vehicles without limited slip. (or motorcycles)

    The only question is viscosity. BMW's G3 (and what the manual on my '20 RT calls for) is 70W80. The trend of going to thinner lubricants is for fuel economy. If they spec'd thinner lubricant in their automotive line, it would follow that they are condensing part numbers and just using their "G3 70W80" across the board in current vehicles.

    I can't see any reason a base viscosity of 75 in GL-5 vs 70 in BMW's G3 would have any adverse effect. It is only going to matter when extremely cold and the difference is negligible.
    and just sorta moved on by
    OM
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  11. #26
    Registered User AKsuited's Avatar
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    The BMW Repair Manual on disc for my bike calls for Castrol SAF-XO for the final drive.

    I found this product, which the supplier says meets those specs: https://www.pelicanparts.com/More_In...-293-972-M1137

    or this, which is likely rebranded Castrol: https://www.bimmerworld.com/Fluids/D...512293972.html

    Some more discussion here: https://www.bmwlt.com/threads/saf-xo-fd-oil.142626/

    Above applies to 2015 R1200GS.

    Harry

    PS: shipping @ Pelicanparts is expensive - I'll check local stores for availability.
    My fleet: 2015 R1200GS, 2017 Toyota Prius Prime (plug-in hybrid)

  12. #27
    Registered User Dann's Avatar
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    The only question is viscosity. BMW's G3 (and what the manual on my '20 RT calls for) is 70W80.
    That's what's written in the user manual but, like mentioned earlier the latest version of the service manual (June 2020) doesn't specify any weight.

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  13. #28
    Somebody needs to go ask their dealership for their free gear lube under the Magnuson Moss Warranty Act (PL 93-637). Since BMW has specified only their proprietary G3 gear lubricant with no corresponding generic specification; ie. viscosity and rating; then under the law they need to provide that proprietary item free of charge.

    After the dealership discloses "that is the same as ... " please report back.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
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  14. #29
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Quote Originally Posted by PGlaves View Post
    Somebody needs to go ask their dealership for their free gear lube under the Magnuson Moss Warranty Act (PL 93-637). Since BMW has specified only their proprietary G3 gear lubricant with no corresponding generic specification; ie. viscosity and rating; then under the law they need to provide that proprietary item free of charge.

    After the dealership discloses "that is the same as ... " please report back.
    That would be a funny interaction to be sure
    Along those lines, here in mass, there is another “right to repair” deal going on. It has to do with car manufacturers trying to limit access to the wireless vehicle diagnostics.
    The “OBD-2” port access had already been settled- in the consumer’s favor some years back.
    OM
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  15. #30
    Registered User stooie's Avatar
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    Quote Originally Posted by PGlaves View Post
    I may be wrong so if somebody actually knows for sure please correct me. But it looks to me like G3 is a designation for automatic transmission fluid with Dexron III G specification. This would seem to be a very light viscosity.

    See: https://www.lubricants.total.com/bus...passenger-cars

    Scroll down to "Automatic Transmission Fluids with Dexron III G specification"

    I may be misreading this but all other mentions of G3 Google found were BMW or Mini specific.

    I did find some "comment" style opinions saying that G3 was the same as 75W90 GL-5 but I didn't find any reliable source saying this.
    Geeze, Paul, What an interesting link.

    I'm pretty sure that Dexron III G3 is an entirely different product. While Dexron automatic transmission fluid is an incredibly widely used product I doubt that it's the same lube we're talking about here. I don't believe it has the extreme-pressure additives required by hypoid gears like those in the final drive. That's why it's listed for automotive transmissions but not for rear axles.

    I suspect the G3 we want is part of the BMW proprietary scheme of G1, G2, etc. that they also use in their automobiles.

    Trivia: Sikorsky Aircraft designated Dexron as an "alternate oil" for use in the main transmission of our S-76 commercial helicopter back in the 1970s. I don't know if it is still listed as such. The lubricant specialist who designated it was very impressed with its qualities. Apparently automatic transmission fluid has a terrific additive package providing excellent viscosity stability vs. temperature, anti-corrosion properties, etc.

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    Bob Stewart
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    2018 RT

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