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Mobil 1 Synthetic 75w-90


Steveyacht

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6 hours ago, Steveyacht said:

Does this meet BMW's minimum requirement for final drive unit?

 

Thanks in advance.

 

S

Morning Steveyacht

 

Technically NO,    BMW requirement is a SAE 70w-80__hypoid axle- GL5 gear oil. The Mobil 1 Synthetic is a 75w-90 GL5 gear oil.

 

Riders have used the Mobil 1 Synthetic 75w-90 in the shift-cam BMW's without issues  but it isn't per BMW spec. 

 

Mopar does service a 70w80 GL5 gear oil,  it is usually much cheaper than the BMW branded 70w80.

 

A number of BMW dealers are/were  still using the older 75w-90 GL5 at service  as the newer  BMW  70w-80 was not available to them. 

 

My personal preference (if you can't find reasonably priced 70w80 GL5 gear oil)  is the  Castrol - Syntrax Long Life 75W-90, but as of late it has become expensive.  

 

If you shop around (like on E-Bay) you can usually find the Mopar 70w80 GL5 gear oil for about $26.00 to $29.00 per 32 ounces with free shipping. VS the BMW 70w80 GL5 that is typically in the mid $40.00 range for only 16.9 ounces (500ml).

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17 hours ago, Steveyacht said:

Does this meet BMW's minimum requirement for final drive unit?

 

Thanks in advance.

 

S

I have used the BMW gear oil, and the Liquid Moly 75W-90 from beemer boneyard.  https://www.beemerboneyard.com/gswefoilkits.html  .  The Liquid Moly is sold in a 1L (1000 mL) jug.

edit:  here are the necessary crush washers/o-rings:  https://www.beemerboneyard.com/fnlcwsr12lc.html 

 

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I use the Syntrax mentioned above, which I understand is what BMW used to spec for the same final drive unit when I used to own a '14 RT, so I see zero issues using it. And I live in hot TX, so prefer the 75/90 myself. And an equivalent like the Mobil1 should be equally fine IMO. But I wanted to buy what used to be the spec oil during warranty, just in case. It's expensive, but lasts 5 oil changes. I wanted to dump the stock dirty fluid asap, but after 3 oil changes, it's still not fully clear. But hope after the 4th one it is:). Will do it at the next oil change, to finally have clear fluid.

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Wow I feel special . Been using 75W / 90 BMW gear oil my dealer has sold to me for my 2023 RS .  Even put a bottle in my friend new 23 GS .  Looking at my manual its 70W 80 . 

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20 hours ago, JCtx said:

My guess is BMW changed it to 75/80 to sell their own oil, since nobody else seems to make it. It's a minimal difference anyway.

Evening JCtx

 

It probably didn't break BMW's heart to be able to specify a difficult to find gear oil that is scarce in the wild but that probably wasn't the reason for the specification change.

 

Around February of 2019  the SAE J306 standard was revised, the revised SAE J306 standard tightened the kinematic viscosity window so BMW probably just adopted the revised standard. 

 

They might have even found that it improved final drive bearing life as I'm sure they thoroughly durability tested it before changing their recommended gear oil spec. The best thing for drive bearing life would probably be a mid viscosity range motor oil, the best thing for the hypoid gear tooth life would probably be an uplevel 80 or 90 weight GL-5 gear oil. 

 

What usually fails in the BMW final drive? It sure isn't the hypoid gear teeth. The 70w80 GL-5 would probably be a good choice GL-5 gear oil for the BMW final drive as the revised spec is tighter controlled. 

 

 

 

 

 

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Castrol Syntrax gear oil comes in two varieties, "Castrol Syntrax Limited Slip" and for non-limited-slip differentials, "Castrol Syntrax Long Life".   The correct one to use for your (for sure hexhead/camhead beemer) transmission and rear drive is Castrol Syntrax Long Life 75W-90, not Castrol Syntrax Limited Slip Gear Oil - 75W-90.

 

The official BMW camhead service manual recommends Castrol SAF-XO gear oil for both the transmission and rear drive.  However, Castrol SAF-XO has been discontinued. 


So, from Castrol's official documentation the following excerpts:

  • "Castrol SAF-XO is specially designed and fully approved by BMW for use in all BMW final drives fitted with conventional (non limited slip) differentials."
  • "Castrol Syntrax Long Life 75W-90: Specially designed and approved by BMW for use in all BMW final drives fitted with conventional (non limited slip) differentials."
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Motorhead1977

Perhaps I'm being overly cautious but until my bike is outside the extended warranty period I'll use the BMW specd gear oil. More expensive - yes, but makes it harder for BMW to deny a warranty claim should I experience a final drive failure, as unlikely as that may be.

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  • 1 month later...
On 12/21/2023 at 4:02 PM, pwillikers said:
  • "Castrol Syntrax Long Life 75W-90: Specially designed and approved by BMW for use in all BMW final drives fitted with conventional (non limited slip) differentials."

So which oil should we use if we have a limited-slip differential? Or AWD?  :4607:

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dirtrider
9 hours ago, JCtx said:

So which oil should we use if we have a limited-slip differential? Or AWD?  :4607:

Morning  JCtx

 

Single track motorcycles don't have a differential as there is only 1 rear wheel so nothing to differentiate.  If it is "All Wheel Drive"  (both wheel drive) then use whatever the front wheel drive type requires. (chain oil, gear oil, hydraulic oil, etc). If the front hub is electric then maybe no oil, grease, or lubrication.

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duckbubbles

Call me dumb, but what is in the additive package of "Limited Slip" vs "Non-Limited Slip" gear oils that can cause damage/wear in our final drives?  Really curious.

 

Frank

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dirtrider
58 minutes ago, duckbubbles said:

Call me dumb, but what is in the additive package of "Limited Slip" vs "Non-Limited Slip" gear oils that can cause damage/wear in our final drives?  Really curious.

 

Frank

Morning Frank

 

It varies by gear oil formulas but the basic thing is not a wear to the gears or bearings thing. It (can be) a seal seepage thing.

 

Limited slip differentials use clutches for the limited slip function. In some units those clutches can have a heavy spring force or other means to hold the clutch disks tight together.  The tight together clutch disks don't always allow the lubricating gear oil get in between the disks so the clutches can chatter  when going around a tight corner or in parking lot turn-in's.  

 

So an additive is added to the (LS) gear oil that wicks in between the clutch disks to prevent clutch chatter. This (penetrating additive) can allow some seal seepage in certain situations.

 

 

 

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duckbubbles

Thank you Dirtrider.  I've been wondering about this in all these gear oil threads!  I've bought Limited slip type gear oil for my older bikes and haven't had an oil seepage problem...yet.  Maybe I'm just lucky.

 

Frank 

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As to your specific question, I've never heard of limited-slip differential oil being a problem on an open differential; it's the other way around. But yes, mentioning 'limited slip' on a motorcycle application makes no sense to begin with. It just generates confusion.

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There are no issues using limited slip lubricant. Basically, It contains an additive that makes it more slippery to keep the clutches from chattering as DR said.  I have never seen it cause seal weeping issues. (36 years owning an auto shop) 

I have used it in my RT and in prior BMW final drives for nearly 20 years.

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dirtrider
13 hours ago, Dan M said:

There are no issues using limited slip lubricant. Basically, It contains an additive that makes it more slippery to keep the clutches from chattering as DR said.  I have never seen it cause seal weeping issues. (36 years owning an auto shop) 

I have used it in my RT and in prior BMW final drives for nearly 20 years.

Morning Dan

 

Most automobiles & light trucks use open bearings in their drive units. 

 

The BMW is (at least was) different,  the hexhead final drives used a clean (sealed) pinion bearing & a clean (sealed) crown bearing. Later 1200 bikes used an open crown bearing but still used a clean (sealed) pinion bearing with it's own internal special grease). 

 

There were problems with gear oil getting in the sealed bearings then diluting the grease or at least causing bearing issues.

 

There were also issues with seal leakage on both pinion & spool. 

 

I haven't been into the new 1250 final drives yet (no parts available for them) so don't know if they still use a clean sealed bearing, or bearings, but why take the chance using non-approved gear oil with an additive that was designed to go where non-LS gear won't ?  

 

  

 

 

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The additive is a friction modifier.  That is all.  It allows the clutches to do their job without sticking and chattering. 

If there was bearing grease dilution, the issue is likely with the bearing seals themselves. If the lubrication additive package was changing the properties sufficiently to attack the seals, It would follow that external seals would fail as well.  Additionally, the Mobil1 75W90 LS product page claims compatibility with gaskets and seals.

 

Additionally, If riders have been using Mobil1 without issue as you said above (and I'm one of them), they have more than likely been using LS rated lube.  Non-LS is pretty much impossible to find at least at the retail level if still available at all. 

 

I did sent a query to Mobil1 as to compatibility. (I was a dealer before I retired)   I'll report their response.

 

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dirtrider
1 hour ago, Dan M said:

 


The additive is a friction modifier.  That is all.  It allows the clutches to do their job without sticking and chattering. 

If there was bearing grease dilution, the issue is likely with the bearing seals themselves. If the lubrication additive package was changing the properties sufficiently to attack the seals, It would follow that external seals would fail as well.  Additionally, the Mobil1 75W90 LS product page claims compatibility with gaskets and seals.

 

Additionally, If riders have been using Mobil1 without issue as you said above (and I'm one of them), they have more than likely been using LS rated lube.  Non-LS is pretty much impossible to find at least at the retail level if still available at all. 

 

I did sent a query to Mobil1 as to compatibility. (I was a dealer before I retired)   I'll report their response.

 

Afternoon Dan 

 

The reason that it is a friction modifier is that it can get in between the clutch plates to lubricate them to prevent chatter.

 

I don't know if you go back far enough to have worked on the old GM 250 L-6. Those engines had a problem with squeaking rocker arms on older well worn in engines.

The hardened rocker arm would burnish the rocker ball to a micro-fit so engine oil couldn't get between the arm & ball to lubricate it, so it would squeak (sometimes very loudly).

 

None of the oil additives at that time would stop the squeak.  But one thing actually did & it worked quite good. 

 

The premier Posi-traction additive at that time was Sperm Whale oil, put about 1/2 of a small bottle of that Sperm Whale Posi-traction additive in the engine oil (squirt it in through the oil filler cap)  & it would mix with the engine oil then seep into the tight rocker to ball interface so within 5-10  minutes  of  engine idling the squeak would slowly go away. And stay away for at least that oil change period & usually one or 2 more. 

 

I wish that Sperm Whale Posi-traction  additive was not banned (I believe to protect the whales)  as that was about best penetrating oil I have ever used. It was also a great cable lube, & would actually seep into tight car door hinges to lubricate those. It sort of made a good gun oil for some applications, it was great at lubricating bolts & triggers.  But it's downside for a gun lube was it's ability to creep so it would eventually end up where you didn't want lubrication. 

 

Obviously Land Rover & BMW engineering think there is enough difference between an LS gear oil & a non -LS gear oil as still specify each for usage in the appropriate drive units.

 

I really don't want to argue this, you are happy with LS gear oil & I don't think it is the best choice so we have both stated our points. Future readers of this thread can  make their gear oil choices based on the  BMW riders manual recommendations as well as personal reasons we have both stated for our choices.     

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Not here to argue. This is a discussion board so if more information is injected it will give thinking readers food for thought.

 

I received a reply from Mobil1 this morning. There is no issue using it in final drives or non limited slip differentials and it will not damage seals or gaskets. It went on to say the obvious, that you can't use non-LS fluid in an LS differential. 

 

Since non-LS lube has become harder to find, I've been using lube with the LS designation. To date, with 3 R series bikes: '04, '11 and '20 and many, many miles, I have had absolutely no issues.

 

My research indicates that the friction modifier, as the name suggests simply lowers friction to eliminate chatter. (From the CRC Trans-x Posi Trac website)

No mention of it being a penetrant or having any "wicking" ability.  If you have seen that it is indeed a penetrant, I'd be interested to read about it.

 

Cheers

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I use what BMW dealers used to sell for our bikes, before using their own fluid... which might be the same stuff. It's Castrol Syntrax 75W/90 long-life, which says on the back it's approved for BMW non-LSDs, so those concerned with that, have a good alternative:grin:. The good news is it lasts for 5 changes, but the bad news is it got a lot more expensive now ($53), and the name changed (Transmax), but probably still a lot cheaper than the BMW fluid. Here's the link for the one I bought back in 2021: https://www.amazon.com/gp/product/B004UD9T0A/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 . Hope this helps.

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Old School
On 12/19/2023 at 5:45 AM, dirtrider said:

Morning Steveyacht

 

Technically NO,    BMW requirement is a SAE 70w-80__hypoid axle- GL5 gear oil. The Mobil 1 Synthetic is a 75w-90 GL5 gear oil.

 

Riders have used the Mobil 1 Synthetic 75w-90 in the shift-cam BMW's without issues  but it isn't per BMW spec. 

 

Mopar does service a 70w80 GL5 gear oil,  it is usually much cheaper than the BMW branded 70w80.

 

A number of BMW dealers are/were  still using the older 75w-90 GL5 at service  as the newer  BMW  70w-80 was not available to them. 

 

My personal preference (if you can't find reasonably priced 70w80 GL5 gear oil)  is the  Castrol - Syntrax Long Life 75W-90, but as of late it has become expensive.  

 

If you shop around (like on E-Bay) you can usually find the Mopar 70w80 GL5 gear oil for about $26.00 to $29.00 per 32 ounces with free shipping. VS the BMW 70w80 GL5 that is typically in the mid $40.00 range for only 16.9 ounces (500ml).

Found it! The Dodge/Chrysler dealership where I work part time actually stocks it.

Mopar Gear Oil.jpg

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Hi all 

Is castrol

Syntrax Universal plus

75w-90

suitable for the final drive ?

Cheers

Mark

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Bluenoser
14 hours ago, Old School said:

Found it! The Dodge/Chrysler dealership where I work part time actually stocks it.

Mopar Gear Oil.jpg

Note that what you have there doesn't quite match what the manual calls for, the manual calls for 70W-80.  I have bought Mopar 70W-80 GL5 at my local Dodge dealer.

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8 hours ago, Dingo55 said:

Hi all. Is castrol Syntrax Universal plus 75w-90 suitable for the final drive?

I don't believe that one is synthetic, so get the 'long life' one. There's very little oil in there, so I wouldn't use anything not fully synthetic. If it is, then it should be equivalent to what others are using. I'm using Syntrax long life because that's what reportedly all BMW dealers used (at least mine did), before BMW came up with their 'own' oil, which is probably the same Castrol stuff, as BMW does not make fluids.

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JCtx

Thanks for that 

Castrol universal plus 75W-90 is fully synthetic API GL-5 rated

Is that all the specifications needed to be met for F/D application?

Cheers

Mark

 

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Dave_in_TX
On 2/9/2024 at 10:52 PM, Dingo55 said:

JCtx

Thanks for that 

Castrol universal plus 75W-90 is fully synthetic API GL-5 rated

Is that all the specifications needed to be met for F/D application?

Cheers

Mark

 

If you have been following this thread, you should know that on the later bikes, BMW specifies 70w80,  not 75w90. Other than that, it should work fine and despite BMW's recommendation for 70w80, the 75w90 should be OK.

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HI 

I've always been a bit curious re the labelling of oil products

My (limited) understanding is that the first number in 75W-90 ie the 75 is connected to ambient temperature (is that correct?)

If so then how can the  number be the same worldwide given such vastly different climatic conditions  

Also do GS variants have a different rating oil requirement (engine and F/D) than a RT variant given that they operate in what I would consider to be vastly different environments?

Cheers

Mark

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Dave_in_TX
29 minutes ago, Dingo55 said:

HI 

I've always been a bit curious re the labelling of oil products

My (limited) understanding is that the first number in 75W-90 ie the 75 is connected to ambient temperature (is that correct?)

If so then how can the  number be the same worldwide given such vastly different climatic conditions  

Also do GS variants have a different rating oil requirement (engine and F/D) than a RT variant given that they operate in what I would consider to be vastly different environments?

Cheers

Mark

No, the lower number is not connected to ambient temperature. The viscosity is measured at two different temperatures. The lower number (75) is the viscosity category at  the lower temperature and the 90 is the viscosity category at the higher temperature.

Some info here:

https://bobistheoilguy.com/?s=viscosity+chart

https://bobistheoilguy.com/viscosity-charts/

https://bobistheoilguy.com/putting-the-simple-back-into-viscosity/

 

 

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Yep, lower number is at cold start, and higher at operating temperature. They typically are measured at 0 and 100C, so 32 and 212F.  At hot ambient temperatures, oils start breaking down quicker, so going a grade higher is perfectly fine in hot climates, and actually recommended (15w50) almost everywhere except the US. I'm sure it's the same thing with the final drive (75w90 vs 75w80), since it was what BMW used before even in the US, and nothing has changed with the final drive. I use 75w90 because it's more readily available, but use 5w40 for the engine, since 5w/40 flows much better when cold (at any ambient temperature) than 15w50, and starts lubricating quicker. Plus I don't track my bike, or ride it hard much at all, so no sense in using that thicker oil in my case.

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dirtrider
17 hours ago, Dingo55 said:

HI 

I've always been a bit curious re the labelling of oil products

My (limited) understanding is that the first number in 75W-90 ie the 75 is connected to ambient temperature (is that correct?)

If so then how can the  number be the same worldwide given such vastly different climatic conditions  

Also do GS variants have a different rating oil requirement (engine and F/D) than a RT variant given that they operate in what I would consider to be vastly different environments?

Cheers

Mark

Morning Mark

 

Gear oil uses a different rating scale than motor oil but the two numbers mean about the same (only on a different scale). 

 

75W-90 is basically a 75 weight gear oil (cold) that doesn't get any thinner than a 90 weight gear oil  would at 100°c.

 

Oil never gets thicker as it heats so the second number is a hot oil viscosity thin-out comparison rating. 

 

75W-140 would still be a 75 weight gear oil (cold) but it doesn't get any thinner than a 140 weight would at 100°c. But it would still be thinner cold than an 80W-90. 

 

So a 75W-90 and a 75W-140 gear oil both start out about a 75 weight gear oil cold but the 75W-140 thins out less than the 75W-90 would at 100°c. But as they heat in use both actually get thinner (lower viscosity)  than either started out. 

 

 

 

 

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Hi all 

Thanks for the replies 

Much appreciated

So in real world terms what is the practical difference between the previous 75w-90 and the new 70w-80?

Are these types of changes simply a commercially based decision?

In numerical terms that doesn't appear to be much of a difference

Is it of a more significant difference in engineering terms?

The temperatures mentioned are controlled laboratory figures? ( is that correct)

 

DR you said earlier that in 2019 the SAe J306 standard was revised 

Out of curiosity 

How does something like that come about ?

Who does that and why?

I'm guessing that must be something independent of any BMW influence

You seem to differentiate between a hypoid axle gear oil and plain gear oil

I've not seen the word hypoid on any of the products I've checked out

 

Looking at my riders manual it calls for

SAE 70W-80 Hypoid axle G3

All the conversation indicates API  GL-5

 Thanks again for the Help

Cheers

Mark

 

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3 hours ago, Dingo55 said:

Hi all 

Thanks for the replies 

Much appreciated

So in real world terms what is the practical difference between the previous 75w-90 and the new 70w-80?

Are these types of changes simply a commercially based decision?

In numerical terms that doesn't appear to be much of a difference

Is it of a more significant difference in engineering terms?

The temperatures mentioned are controlled laboratory figures? ( is that correct)

 

DR you said earlier that in 2019 the SAe J306 standard was revised 

Out of curiosity 

How does something like that come about ?

Who does that and why?

I'm guessing that must be something independent of any BMW influence

You seem to differentiate between a hypoid axle gear oil and plain gear oil

I've not seen the word hypoid on any of the products I've checked out

 

Looking at my riders manual it calls for

SAE 70W-80 Hypoid axle G3

All the conversation indicates API  GL-5

 Thanks again for the Help

Cheers

Mark

 

Morning Mark

 

I don't know why the SAE J306 standard was revised, in a lot of cases it's the trucking industry that drives gear oil revisions as they are the major user of gear oil.

 

It could be they (the API) is just tightening up the gear oil categories with more closer controlled divisions. A 75w90 gear oil can actually be within 1 cST of 80w & still be rated as a 75w or within 1 cST of a 95 & still be a 90. 70W-80 tightens that window a little. 

 

Probably in real world normal usage the final drive wouldn't know a 75-90 from a 70W-80 as long as the additive package was similar. 

 

I have seen this in other areas with the API tightening up the rating categories as things like bridged vents (at extremely low temps) & oil packing (small housings with very thick gear oil allow the gear oil to pack away from the needed lubrication areas).

 

There is also the fuel economy gain in tighter controlled thinner gear oils. Not so much for the rider/driver in the real world but on the emission dynos & in coast down numbers used for part of the fuel economy ratings. 

 

Early on (when BMW first specified the 70W-80 gear oil) BMW dealers were still putting in 75-90 as they couldn't get the proper 70W-80 gear oil from BMW. 

 

On an out-of-warranty BMW, personally, I wouldn't fret a minute in using a GOOD QUALITY, non-LS 75-90 GL5. On a still-in-warranty BMW I would still use the BMW required 70-80 GL5. The service amount is so small you can get a number of gear oil changes from a single quart. 

 

If there was a final drive issue while still under warranty & you are doing your own service BMW could (not that they always will)  but they definitely could ask for your oil & gear oil receipts to prove that you used the correctly specified gear oil. You might be able to eventually beat that in court  but getting that win would cost WAY/WAY more time, money, & vehicle miles than just using the proper gear oil.  Plus, if you are fighting a warranty issue there is a good chance that your motorcycle could be sitting out-of-service  (taken apart) during the dispute period. 

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