75W-90 vs 75W-140 for gearbox.

[Wally E]

I am using 75W-90 in gearbox and FD. I have to say that the gearbox is slick and smooth when cold and noticeably more clunky when fully warmed up.

I have a feeling that 75W-140 might smooth things up. I'm going to try the thicker oil this weekend and report back.

Anyone else tried 75W-140 in the gearbox?

Both grades are recommended by BMW for gearboxes BTW.

[Marty Hill]

I've used both for years. Either way works for me.

[dirtrider]

Evening Wally

 

They are both 75 weight gear oils. The only difference is the 75-140 doesn't thin out as much at very high temps.

 

You won't get an actual comparison until you get some miles on the new gear oil & it shears down.

 

If you want to compare gear oils then you will have to change to NEW 75-90 then try it, then change out to the 75-140 & see if you can tell the difference.

 

They all usually shift better with new (un-sheared) gear oil-- that is why you keep reading on the internet how this or that gear oil is always better that what was being used.

 

If you want to compare a new gear oil to gear oil that has 6,000 miles on it then run the new gear oil for 6,000 miles. Problem is, by then you forgot how the old gear oil acted 6,000 miles ago.

[Wally E]

Evening Wally

 

They are both 75 weight gear oils. The only difference is the 75-140 doesn't thin out as much at very high temps.

 

You won't get an actual comparison until you get some miles on the new gear oil & it shears down.

 

If you want to compare gear oils then you will have to change to NEW 75-90 then try it, then change out to the 75-140 & see if you can tell the difference.

 

They all usually shift better with new (un-sheared) gear oil-- that is why you keep reading on the internet how this or that gear oil is always better that what was being used.

 

If you want to compare a new gear oil to gear oil that has 6,000 miles on it then run the new gear oil for 6,000 miles. Problem is, by then you forgot how the old gear oil acted 6,000 miles ago.

 

So, here is my report on the above.

 

Let me say at the start that I did not use any BMW branded oil.

I did some research, studied the spec sheets, and satisfied myself as to the following:

 

Castrol/BMW branded SAF-XO 75W-90 is equivalent to Castrol Syntrax Long Life 75W-90.

 

Castrol/BMW branded SAF-XJ 75W-140 is equivalent to Castrol Syntrax Limited Slip75W-140.

 

Take a look at these links, and yes I know there are some very subtle differences, but IMHO they are essentially equivalent.

 

http://www.benquip.bz/uploads/produc...J_B1174_96.pdf

http://www.salube.co.za/downloads/td...ife-75w-90.pdf

http://www.frontier.ro/files/pdf/75W140%20LIM.pdf

 

Both Syntrax grades are readily available in motor spares outlets in my neck of the woods. I could have got the BMW branded stuff from the dealer, but chose to go the el cheapo route.

 

I first tried fresh Castrol Syntrax Long Life 75W-90 in the gearbox for about 500km, drained that and filled with fresh Castrol Syntrax Limited Slip75W-140 for another 500km or so. I figured this would give me the fairest comparison.

 

My carefully calibrated left foot and seat of the pants tells me that the 75W-140 gives a noticeable but not miraculous reduction in the "clunk" when shifting with the engine/transmission fully warmed up compared to 75W-90. I have always found the clunk particularly noticeable on the 2nd to 3rd upshift.

 

Shifting after moving off from cold in both cases gives the same very smooth shifting. The clunkiness only comes in when things warm up.

 

I realise that the clunk is probably a very subjective thing, annoying to some, a non-issues for others. Each to his own. I am happier with the

thicker goo, and if my transmission self destructs in the future (which I doubt), then so be it.

 

BTW I do not intend using anything but 75W-90 the FD.

 

Hope this may be of interest to some.

 

[lkchris]

We don't get Syntrax in the USA nor anything equivalent, and consequently must buy from BMW or Land Rover dealers. Our auto parts business is dime store stuff for the most part.

[BrianM]

AutoZone seems to have some Castrol gear oil with the Syntax name.

 

http://www.autozone.com/greases-and-gear-oil/gear-oil/castrol-syntrax-limited-slip-gear-oil-sae-75w-90-32-oz-/991561_0_0/

[racer7]

If you put the bike on the centerstand in neutral with the engine running, it is easy to see that the 140 has more fluid drag- the rear wheel will turn a good deal faster than the 90.

In some circumstances this can translate to smoother or easier shifts on bike or cage type dog boxes which need moving gear bits to work smoothly.

 

Based on what I've seen re he above, I'd be happy with the 140 if I rode in a warm climate and would stick with the 90 in a colder spot.

 

Remember, on bikes with the big hole FD, the bearings are outside the gear lube so all its doing is lubing the gears themselves- which are rugged and not prone to failure.

[WDH]

Riding a newly acquired - low mileage (32,000 km) 5/95 R1100RT and had the clunkiest gearbox of three BMWs owned. Shifts 1-2 were bad, 2-3 were horrible.

 

Did a full service including transmission using Motorex Prismazx 75W/90 Synthetic and cannot believe the difference. So far, a complete solution to the problem.

 

I note the comments regarding longevity of the fix. Appreciate the suggestions on the forum which led me to this result.

 

Wayne

[6speedTi]

Even though my 2012 is fairly new, every time I serviced the Gear box my shifts went smoother. Over time they seem to slack off and begin to get a bit rough. This was discussed before on one of the forums. New fluid has an affect and seems to break down to some point which affects the shift characteristics. Although the gear oil is a top synthetic quality and will last a long time something in the chemistry of the oil changes rather quickly.

[dirtrider]

Morning 6speedTi

 

Yes, gear oil's shear with usage. The best way to shear gear oil is to pass it through meshing gears under load (what a manual trans does best)

 

The less polymers in the gear oil the less it should shear with usage so some of the up-level synthetic gear oils will last longer (stay at original viscosity) than same-viscosity conventional gear oil under the same working conditions.

 

That is why I put little notice to all the posts that say XY or XYZ gear oil shifts better than what was in the trans.

 

They almost always shift better after any new gear oil is installed. The bottom line is-- how do they still shift after 5,000 miles on the gear oil?

 

 

[Dave_in_TX]

Morning 6speedTi

 

Yes, gear oil's shear with usage. The best way to shear gear oil is to pass it through meshing gears under load (what a manual trans does best)

 

The less polymers in the gear oil the less it should shear with usage so some of the up-level synthetic gear oils will last longer (stay at original viscosity) than same-viscosity conventional gear oil under the same working conditions.

 

That is why I put little notice to all the posts that say XY or XYZ gear oil shifts better than what was in the trans.

 

They almost always shift better after any new gear oil is installed. The bottom line is-- how do they still shift after 5,000 miles on the gear oil?

 

And oils with large viscosity spreads such as 75W140 often shear more rapidly than ones with smaller spreads such as 75W90 so after 5k miles the difference may be much smaller than at zero miles.

[Glockdawg]

I'm going to commit some heresy here.

 

I believe that the oil being used is too thick and this is responsible for some of the shifting issues associated with BMW (Getrag) transmissions. Most automotive transmissions now use ATF in them. The new generation ATF's offer many benefits that make it a sensible alternative. Now having written that, I won't go that far in making my case, but think some of that logic does apply. So, in that vein I went thinner and went with Red Line MTL, which is a 75-80W

http://www.redlineoil.com/product.aspx?pid=45&pcid=7

 

It is a GL-4 rating rather than GL-5, but from my research I don't think that it matters at all.

 

I've been running this oil for about 6K miles now and the bike shifts much better than with stock BMW oil. I will send a sample off to get tested when it's time for a change. However, for now, I am very satisified with the results.

[dirtrider]

Afternoon Glockdawg

 

BMW is pretty specific in recommending an API GL-5 gear oil so using a GL-4 rated gear oil with about half the Extreme Pressure additives is contrary to BMW recommendations to maintain warranty coverage.

 

Use what ever makes you happy but for others that read this thread a GL-4 gear oil is not what BMW has tested for hundred of thousands of miles & is against BMW recommendations to maintain warranty coverage.

[Guest Kakugo]

I've used 75W-90 in the first two years of ownership, then shifted to 75W-140 according to guidelines given by Castrol BMW to dealers in order to sell a more expensive product improve performances.

 

In my experience the lighter grade is just better in any condition.

[Glockdawg]

Afternoon Glockdawg

 

BMW is pretty specific in recommending an API GL-5 gear oil so using a GL-4 rated gear oil with about half the Extreme Pressure additives is contrary to BMW recommendations to maintain warranty coverage.

 

Use what ever makes you happy but for others that read this thread a GL-4 gear oil is not what BMW has tested for hundred of thousands of miles & is against BMW recommendations to maintain warranty coverage.

 

Quite so. However, GL-4 would seem to be more than adequate in our transmissions. If you read up on the development of GL-5, the specifications really don't apply to us anyway. It was developed specifically for high speed military applications. It clearly is superior, however, realistically it's overkill. The oil I'm using was developed by Red Line for BMW Getrag made manual transmissions, only they were automotive not specific to motorcycles.

 

It's kinda like the tribal knowledge about using Hypoid oils in the transmission, where there are no hypoid gears present. Whatever oil people use it must be rated "MT" and not hypoid, because that means for use in manual transmissions.

[dirtrider]

clip--

It's kinda like the tribal knowledge about using Hypoid oils in the transmission, where there are no hypoid gears present. Whatever oil people use it must be rated "MT" and not hypoid, because that means for use in manual transmissions.

 

 

Morning Glockdawg

 

Automotive manual transmissions (most anyhow) have synchronizers that have to brake spinning parts to allow shifting (not so in manual motorcycle transmissions), so you are looking at apples to oranges when comparing automotive MT requirements to motorcycle requirements.

 

It's difficult to compare synchronized automotive gear boxes to sliding-dog motorcycle transmissions.

 

Most automotive applications would just love to use the superior lubricating GL-5 gear oil but can't due to most GL-5 gear oils having too much EP additives to allow the synchronizers to brake correctly.

 

With the many/many thousands of miles of BMW durability testing & most likely long term supplier dyno testing, plus the full helical gears sets in the BMW motorcycle transmission, you would think that if a GL-4 oil met BMW's long term wear criteria then the recommended spec would be either a GL-4 or GL-5 gear oil. It isn't as only GL-5 is specified.

[RTJohn]

I've been using Royal Purple GL5 75W-90 for a little while now with good results. I switched from Mobil 1 because it doesn't have the LS rating that M1 does. It's more expensive than M1 but that's OK too.

[Glockdawg]

clip--

It's kinda like the tribal knowledge about using Hypoid oils in the transmission, where there are no hypoid gears present. Whatever oil people use it must be rated "MT" and not hypoid, because that means for use in manual transmissions.

 

 

Morning Glockdawg

 

Automotive manual transmissions (most anyhow) have synchronizers that have to brake spinning parts to allow shifting (not so in manual motorcycle transmissions), so you are looking at apples to oranges when comparing automotive MT requirements to motorcycle requirements.

 

It's difficult to compare synchronized automotive gear boxes to sliding-dog motorcycle transmissions.

 

Most automotive applications would just love to use the superior lubricating GL-5 gear oil but can't due to most GL-5 gear oils having too much EP additives to allow the synchronizers to brake correctly.

 

With the many/many thousands of miles of BMW durability testing & most likely long term supplier dyno testing, plus the full helical gears sets in the BMW motorcycle transmission, you would think that if a GL-4 oil met BMW's long term wear criteria then the recommended spec would be either a GL-4 or GL-5 gear oil. It isn't as only GL-5 is specified.

 

No issue with anything you've written with a however. That being I wouldn't bet on BMW doing alot of expensive and lengthy oil testing. I would be more inclined to bet BMW inc chooses fluids based more on bean counters than engineers.

[lkchris]

That being I wouldn't bet on BMW doing alot of expensive and lengthy oil testing. I would be more inclined to bet BMW inc chooses fluids based more on bean counters than engineers.

 

You hear that a lot, but it remains inane.

[Glockdawg]

That being I wouldn't bet on BMW doing alot of expensive and lengthy oil testing. I would be more inclined to bet BMW inc chooses fluids based more on bean counters than engineers.

 

You hear that a lot, but it remains inane.

 

 

1: empty, insubstantial

2: lacking significance, meaning, or point : silly

 

How so?

 

A member posts about his belief that BMW does extensive testing on oils before selecting which vendor to purchase the product from. I give a shorthand reply stating that it is my belief that BMW, and almost all companies for that matter, don't do the testing themselves, but instead issue a set of specifications and put them out to bid. The oil company that meets their design specifications, delivery demands and whatnot at the lowest pricepoint, gets the contract.

 

This is my 1st RT, but my 5th beemer over the past 20 years or so, so I am familiar with the company, their practices and products.

 

[dirtrider]

That being I wouldn't bet on BMW doing alot of expensive and lengthy oil testing. I would be more inclined to bet BMW inc chooses fluids based more on bean counters than engineers.

 

You hear that a lot, but it remains inane.

 

 

1: empty, insubstantial

2: lacking significance, meaning, or point : silly

 

How so?

 

A member posts about his belief that BMW does extensive testing on oils before selecting which vendor to purchase the product from. I give a shorthand reply stating that it is my belief that BMW, and almost all companies for that matter, don't do the testing themselves, but instead issue a set of specifications and put them out to bid. The oil company that meets their design specifications, delivery demands and whatnot at the lowest pricepoint, gets the contract.

 

This is my 1st RT, but my 5th beemer over the past 20 years or so, so I am familiar with the company, their practices and products.

 

Afternoon Glockdawg

 

That doesn't make sense to me. Why would BMW spec an inferior oil? They do test with different gear oils (both on road & on drivetrain dynos but way spec a gear oil that will ultimately cost them money in warranty work?

 

Specified gear oil that is customer paid for at change time costs BMW nothing. Inferior lower cost oil could cost them, so where is BMW's gain in this?

[Glockdawg]

That being I wouldn't bet on BMW doing alot of expensive and lengthy oil testing. I would be more inclined to bet BMW inc chooses fluids based more on bean counters than engineers.

 

You hear that a lot, but it remains inane.

 

 

1: empty, insubstantial

2: lacking significance, meaning, or point : silly

 

How so?

 

A member posts about his belief that BMW does extensive testing on oils before selecting which vendor to purchase the product from. I give a shorthand reply stating that it is my belief that BMW, and almost all companies for that matter, don't do the testing themselves, but instead issue a set of specifications and put them out to bid. The oil company that meets their design specifications, delivery demands and whatnot at the lowest pricepoint, gets the contract.

 

This is my 1st RT, but my 5th beemer over the past 20 years or so, so I am familiar with the company, their practices and products.

 

Afternoon Glockdawg

 

That doesn't make sense to me. Why would BMW spec an inferior oil? They do test with different gear oils (both on road & on drivetrain dynos but way spec a gear oil that will ultimately cost them money in warranty work?

 

Specified gear oil that is customer paid for at change time costs BMW nothing. Inferior lower cost oil could cost them, so where is BMW's gain in this?

 

Who said anything about an inferior product? Which is better Castrol or Golden Spectro? BMW has used both as a vendor and rebadged their products as BMW brand oil. (And, I believe Shell too) As far as I'm concerned, both products are excellent high end products. So is Red Line, Mobil 1, etc.

 

You said that you don't understand why BMW buy a cheaper (not inferior) oil when the customer is the one who pays the price. True, in a way, but not exclusively. The customer does pay, but profit margins are what we're talking about. If BMW can sell a liter of gear oil for $50, but only pay $5 for that liter. You get the idea.

 

As to my original transgression: GL-4 and GL-5 are almost identical in chemical compositions. The differences between those two grades of oils are minimal at best. The biggest differences between those two grades of oils as far as I can tell (by hanging out in BITOG and other sources) apply to things not found in our Getrag transmissions.

 

I originally shared my use of Red Line as a way of saying there are other products out there that work and work well. Thinking outside of the box. It was originally recommended to me by a professional independent mechanic who uses it in his personally owned BMW motorcycles. He's been using this product for many years and many miles without an issue. I did and I'm happy with the results. Will it blow up my transmission? No, it won't. Period. As long as I am reasonable and follow recommended fluid change intervals, which I do religiously.

 

If anyone wants to use BMW branded products exclusively I'm cool with that, but there are other ways to skin a cat.

[dirtrider]

Morning Glockdawg

 

 

 

Like I said above you use whatever makes you happy.

 

The BMW specification & recommendation is still a GL-5 gear oil.

 

It really doesn't matter how you try to justify something different, BMW still recommends GL-5 gear oil.

 

 

[RTJohn]

I was doing some research for a procedure at work and looking at gear oil specs. Something that stood out is GL-4 oil can be used in hypoid gears running at low speeds. For higher speeds GL-5 is recommended. I'm pretty sure our trannies run at pretty high speeds. Just saying...