BMW Gear Oil SAE 75W90

[Dundee387]

Hey guys stupid question here, I've got the BMW gear oil left over from a change about a year ago on my K bike.

 

Gonna change the RT final drive fluid and was wondering if this is still ok? or does it deteriorate as brake fluid does from a unsealed container?

 

Is this still the spec for the oil @ 180ml, or has it changed to Castrol SAF-XO?

 

Thanks !

 

[dirtrider]

Evening Dundee387

 

I presume this is on your 2006 1220RT? (correct)

 

Gear oil will degrade in storage over time but not in that year or so you have had it unless you left the cap loose or open.

 

The spec is still 180 Ml.

 

My personal choice is the Castrol SAF-X0 as that is what BMW recommends & what the bike was tested with. Actually I use the Land Rover LRN 7591 75-90 as it is the same oil as SAF-XO & in my area a LOT cheaper.

 

Probably no reason not to use another brand Uplevel synthetic 75-90 gear oil but SAF-X0 is the BMW recommendation.

 

[Urban Surfer]

Would there be any harm in using 75 140 gear lube? I have some left over from changing my truck diffs.

[Guest Kakugo]

Would there be any harm in using 75 140 gear lube? I have some left over from changing my truck diffs.

 

My local BMW dealer recently started using 75W-140 gear oil in boxers hence no problem.

However personally I am not happy with it and will ask to go back to the old 75W-90.

[Dundee387]

Thanks!

[hopz]

The 140 gear lube thing started when the final drive issues started. I personally believe it was a non-scientific/non-engineering approach to solve the problem.

 

Since then the factory has clarified that the recommended lube in the final drive is 75w-90 however the volume has been reduced to 180 ml.

 

Your dealer can and probably will do what he wants. What is important is you getting what you want.

[Bob_Minor]

I was at my dealer last week and noticed that BMW now has a branded 75W-90 synthetic gear oil labeled as "Final Drive Gear Oil". Kinda high priced at $23 bucks a quart, but then it is enough for 5 changes.

[Rapala 50]

I thought I read here that Mobil 1 75-90w LS was o.k. to use so that's what I put in on my last trans/FD change, What this a mistake ?

[dirtrider]

I thought I read here that Mobil 1 75-90w LS was o.k.

 

 

Evening Rapala 50

 

I'm not sure where you read that but it sure isn't BMW spec.

 

The LS stands for Limited Slip (type of positraction). LS gear oil's claim to fame is it's ability to seep in between the limited slip clutch disks & prevent them from chattering. That Limited Slip additive used to be made from Sperm Whale oil but that was long ago before it was banned. Now it is a synthetic made additive that actually makes a good penetrating oil in it's own right.

 

The BMW 1200 final drive is a pretty hearty unit that by design shouldn't be gear oil critical or require anything special for a gear oil.

 

As far as gear tooth protection, about any GL-5 gear should work OK regardless of if it has an LS additive in it or if it is a 75w90 or 75w140. The possible issue in using an LS type gear oil is it can migrate to places it isn't wanted (like into the sealed crown bearing chamber) or seep through the pinion seal. There have been some reports on the hexhead final drive of gear oil getting into & contaminating the crown bearing grease.

 

BMW doesn't specify an LS type gear oil so personally I wouldn't use one myself. Nothing to gain & something to lose if it migrates into the sealed crown bearing chamber. Some riders do use an LS gear oil & seem to have no issues. I have no idea if it "would" be a problem, just that it "could" be a problem, so why using something that BMW didn't originally test with or feel a need to specify.

 

Same with 75w140 gear oil, BMW goes out of it's way to NOT specify a 75w140 gear oil, the BMW final drive just doesn't get hot enough to get any gain from a 75w140 gear oil so why use it.

 

The darn thing only holds 180 Ml (that's only a hair over 6 ounces) so you get 5 final drive changes out of a quart. I guess I can't understand not using the correct (BMW spec) gear oil.

 

Same with the trans, about any GL-5 gear oil will protect the gears as they just don't run under much loading. But it has sealed (grease filled bearings) so why use a gear oil that could possibly compromise those sealed bearings. Personally I doubt it is an issue but BMW doesn't specify an LS additive gear oil so I doubt they tested the trans with it. Why use an LS gear oil if you don's absolutely have to. It only holds a quart so it isn't an expensive ordeal to use the correct GL-5 gear oil.

 

 

[JayJay]

I was at my local dealer last weekend because I wanted to get some more of what I had been using - BMW 75W-90 Super Synthetic (the pink stuff) - for a tranny and FD fluid change. Dealer told me that BMW was no longer distributing that product but had recommended something that was about $90/quart that they weren't carrying! So I ended up with what their shop is using, a 75W-90 Synthetic GL-5 (~$20/liter) marketed for "motorcycles with driveshafts and dry clutches" with a recommended change interval of 100K miles. I don't recall the brand. I'm definitely not planning to leave it in for 100K miles, but may look to find the Castrol or Land Rover equivalent for when I next change it out. I do my FD at 12K and tranny at 24K.

 

JayJay

[Rapala 50]

Where might one find the Landrover of Castrol oil, ? And should I be using this in both the Transmission and FD ?

[dirtrider]

Evening Rapala 50

 

The Castrol SAF-X0 75w90 (BMW specified gear oil) is difficult to find in the United States as it wasn't cleared for import until just recently. Some BMW dealers now sell it but a pretty hefty price (like REAL expensive).

 

The LRN 7591 75-90 (same as SAF-XO) is available at most Land Rover dealers. That can vary in price depending on the Land Rover dealer. My local Land Rover dealer is not that expensive. I have also seen both the SAF-XO & LRN 7591 75-90 on E-Bay for reasonable prices, but watch the shipping cost. (I bought 4 liters or SAF-XO on E-Bay last fall for $8.00 as quart + free shipping but that was a real find.

 

On your 2008RT trans?-- The original BMW spec was straight 90 weight GL-5 gear oil. That is difficult to find in the US as most is either 80w90 or 75w90. Either of those usually meets the API 90 weight criteria though.

 

There was a BMW service bulletin about a year or so ago that said the SAX-X0 was now authorized for the trans on the hexhead. Some of us have been using multi weight synthetic in the hexhead trans for a long time now (BMW just justified it).

 

From my personal bikes & personal observation the BMW hexhead trans is kind of finicky on what brand & type of gear oil makes them shift the best both hot & cold. My 1200RT shifts best (by far) with LRN 7591 75-90 in it. My 1200GS doesn't seem to care what it has in it. So basically try the LRN 7591 75-90 in yours, if that shifts good or better than what you have now then you can't go wrong with the LRN 7591 75-90. If that shifts worse then try some others but my suggestion to not use a LS gear oil if possible. Some swear by Royal Purple & other claim Amsoil 75-90 shifts best. That could very well be the case for THEIR trans as I mentioned above they all seem to like something different so try a few until you find what shifts the best.

 

For the final drive my recommendation is to stay with the BMW recommended SAF-XO or the LRN 7591 75-90 as that has BMW's blessing.

 

[Dundee387]

Land Rover dealer wants $20.81/qt. for the LRN 7591 75w 90 here in CT.

 

I paid nearly $48/qt. last year for the Castrol SAF-XO when I did my transmission change. Man did it shift like a hot knife through butter after that change...

 

I'm gonna go with the LR 7591.

[longjohn]

$23/qt for bmw branded saf xo here in socal at the bmw motorcycle dealer. That's way cheaper than it used to be.

[marcopolo]

$23/qt for bmw branded saf xo here in socal at the bmw motorcycle dealer...

 

Just curious as to what you mean by "BMW-branded SAF-XO". SAF-XO is a Castrol product. To my knowledge, only BMW in the U.S. has BMW-branded oils and lubricants. Are you saying that BMW U.S. has an agreement with Castrol to package its gear oil in a BMW-labelled bottle? And even if that were the case, how would you know whose gear oil it was? Here in Canada we've had easy access to Castrol SAF-XO from the get-go. I'm asking because I may be moving to the U.S. by the end of the summer and I've always found this BMW-branded oils business to be a bit curious.

[dirtrider]

[marcopolo]

 

Got it. Thanks.

[malcolmblalock]

This discussion grabbed my attention to the point that I rode about 25 miles this afternoon to buy two quarts of the Land Rover oil. I figured that if that's what the bike needs, I'll use it. I used Mobil 1 75/90 LS oil on my 05 RT and the same on my current 09 RT. Final drive failures on each of them; I have no idea what caused the failure, but I paid for the 05 replacement and warranty paid for the 09 replacement. I have no idea as to whether or not the LS oil had anything to do with the failures on either bike. But, reading DR's comments, it makes me wonder....

 

Alas, the local Land Rover had no oil in stock. They had it in bulk, but weren't interested in drawing out 2 quarts to sell. They can order it at $28 per quart.

 

I looked at the local auto-supply stores and had trouble finding a synthetic 75/90 NON LS oil. Most were for limited-slip differentials. I did find Lucas Oil Products Synthetic SAE 75W-90, which is NON LS.

 

So, my question is whether the Lucas Synthetic NON LS oil is okay for the transmission and final drive on an 09 RT? All comments are welcome.

[Rapala 50]

After posting the other day and the response D.R. Had I got on EBay and ordered a quart of the LRN 7591 ( only one left though ) . So I decided to check again today ( no luck on the Land Rover ) but someone out of Troy, N.Y. Was selling 7oz bottles ( 206ml )of BMW Final Drive Fluid SAF-XO for $ 9.00 plus $ 5.00 shipping. I purchased 2 bottles for $ 25.44 shipped to my door ( had to pay tax ) . Just an FYI for anyone looking to do there FD......

[ed may]

If the Final drive failures are from diff fluid migration into unwanted spots, it makes sense to me that the 75W-140 would do no harm, but could help prevent migration. I just did my fluid change and used Castrol MTX Full Synthetic 75W-140. After a long 2 up ride on a hot day, that diff felt hot to the touch, so I would think that the oil is getting hot enough for that 140 viscosity to help.

[dirtrider]

Afternoon Ed

 

Both 75w90 & 75w140 are 75 both weight gear oils. The 75w140 NEVER gets any thicker it just doesn't thin out as much as 75w90 at very high operating temps.

 

Hot to the touch is a far cry from the 100°c that the 140 part is rated at.

 

[WestyLancs]

MY 06 RT came with the original 'sealed to death - lifetime fill'

 

I took it upon myself to change it at approx. 30,000 miles and used Castrol SAF/XO as specified - not too difficult to get hold of here in the UK,

but has since been superseded, I believe.

 

Final drive failed at 50,000 miles, despite that, so it isn't necessarily the oil that's the cause, or prevention.

 

BMW covered 50% of the parts cost as goodwill 3 years out of warranty as the drive failure was 'unusual' according to the tech.

I never did find out what had actually failed, but for a £500 / $750ish, saving, I'll stay ignorant.

[ed may]

Hi DR, I have read, and understand multi viscosity oil as follows, the 75W part means it is a 75 viscosity (thinner) when cold, and the second number, the 90, or the 140, means that is the viscosity hot (usually 100c). So, if you use 75W 90, and the diff never gets to 100c, that oil will be operating somewhere between it's cold, and hot range, I would think, more toward the hot, so closer to the 90 viscosity. That means if you are using 75W 140, with the same temp philosophy, then that oil would be running closer to the 140 viscosity range. So, I agree with your 3rd sentence, but not with your first two sentence. Am I wrong?

[dirtrider]

Afternoon Ed

 

75w140 gear oil never gets to 140 viscosity even at 100°c

 

The 140 in 75w140 means that the gear oil doesn't THIN OUT any more than 140 weight would at that same 100°c. Basically it never get any thicker it just doesn't thin out as much at high temps.

 

[ed may]

Hi D.R. You are obviously very well informed about alot, and I have alot of respect for you. Therefore, I have a hard beleiving you are wrong, but I think you are. First of all, the W stands for Winter, correct? If so, it applies to the first number, right? If so, the 75W 90 will be 75 viscosity (thinner) when COLD, and closer to 90 viscosity (thicker) when near 100c. The 75W 140 will be 75 viscosity (thinner) when COLD, and closer to 140 viscosity (thicker) when near 100c. Now if you compare a 5W 30 to a 20W 30, they will both act like 30 viscosity (thicker) as they approach 100c. BUT, on cold mornings, the 5W will be thinner than the 20W until it heats up. That is why 5W or 0W is recommended for engines starting in very cold climates. Modern engines are built to closer specifications than in the past, if a 20W 30 is used in a new car instead of a recommended 5W 30, when started in cold weather, the oil will be too thick to circulate properly. The main number here is the 2nd number, since it is considered "operating temperature" in engines. Now I understand that diffs don't run at the same 100c "operating temperature" but it will be closer to the hot temp rating than the cold temp rating. Therefore, if you take a 75W 90 and a 75W 140 and test them both at the same hot temperature, even if it's not at the 100c rated temp, the 75W 90 will be thinner than the 75W 140. THEY WILL BOTH ACT THE SAME COLD, BUT DIFFERENTLY AS THEY HEAT UP. Can someone else please "weigh" in here?

[dirtrider]

Afternoon Ed

 

Motor oil & gear oil NEVER gets any thicker as it heats it only thins out as it gets hotter.

 

75w140 is a 75 weight gear oil that doesn't thin out any more than a 140 weight gear oil would at 100°c.

 

 

Some believe that "W" stands for winter, I haven't ever seen that as fact in any of the SAE oil documents. From what I have been able to find the "W" is just a designation of one type of testing vs. another.

 

[ed may]

Well now I am completely confused. I know when oil comes out of a hot engine it flows faster than if that oil was cold. So I searched for better articles. Check out this document.

http://www.kewengineering.co.uk/Auto_oils/oil_viscosity_explained.htm

It is very confusing. It states that the first number is the base oil viscosity, being the 75W. It then explains, I think, that a higher second number means it will not thin out as much as it reaches operating temp, and a lower second number means it will thin out quicker as temperature rises. So if the second number is 140, it will act like a 140 weight oil when it is hot, meaning it won't get as thin as a 90 weight when it is hot. So I understand now, a 5W 30 will act like a 5 weight when cold, but when it's hot, it will act like a hot 30 weight, BUT that hot 30 weight is still thinner than the cold 5 weight! A 5W 50 will not get as thin/as quick. I think my head just blew up. The big catch here is, that second number means it will act as a thicker oil would, WHEN HOT. Thats better than it acting like the thinner first number, WHEN HOT. I understand now, DR, you da man. There are alot of misled people out there on this topic.

 

[dirtrider]

clip--- So I understand now, a 5W 30 will act like a 5 weight when cold, but when it's hot, it will act like a hot 30 weight, BUT that hot 30 weight is still thinner than the cold 5 weight! A 5W 50 will not get as thin/as quick. I think my head just blew up. I understand now, DR, you da man.

 

Evening Ed

 

"BUT that hot 30 weight is still thinner than the cold 5 weight" -- There it is in a nutshell.

 

[ed may]

I can see everyone is scratching their head over this, and not sure what to say. I was expecting alot of feedback here. I have been thinking alot about this (probably too much) and I am trying to simplify it in my head. The bottom line here is 75W 90 and 75W 140 will act the same cold. But as soon as it starts to heat up, the 75W 90 will get thinner than the 75W 140.

[dirtrider]

Morning Ed

 

Yes, in it's simplest form that is basically true.

 

 

But there is LOT more to the oil (both gear & motor) than JUST the base oil viscosity (75w in this case) & the 100°c rating 75 or 140 in this case.

 

First off, the base 75 viscosity is just a flow number at or below a temperature. It really isn't a gauge of lubricity at that temp.

 

There are a lot of other factors in considering gear oil choice than just the viscosity rating.

 

Using a gear oil that is thicker than required to protect the gear tooth contact & bearings is counterproductive as thicker oil adds nothing but higher friction therefore higher operating heat & higher power requirements to turn.

 

The other issue is oil shearing, as a rule the larger the number between the low & high number the more VI improvers needed to allow that viscosity spread. VI improvers (polymers) really add no lubrication as they are basically just oil thickeners. Those VI improvers also tend to shear (break apart) when passed through the gears so that nice sounding 75w140 can shear down to a much lower viscosity with usage. High end synthetics as a rule contain less VI improvers but they are not immune to oil shearing.

 

When it comes to the BWM final drive & seal leakage there are other things to consider. Like the oil additive package, some gear oils have additives that continually condition seals & others (like some synthetic gear oils rated for higher mileage) have less seal conditioner as they are after less total friction & are mainly blended for use in late model automobiles/trucks with high tec seals.

 

The other thing to consider is HEAT. The 2005-2009 BMW 1200RT uses a NON VENTED final drive. That means the very small air space in the final drive is sealed. That sealed in air expands & compresses with heat. So, the hotter the final drive operates the higher the internal pressure on the oil & seals. In this case a thicker gear oil at operating temps MUST produce more operating heat therefore producing higher internal pressures.

 

Again, using a thicker gear oil than required to protect the gears & bearings gains nothing except higher operating temps & more fuel usage, plus, on the BMW 1200RT hexhead higher internal final drive pressures.

 

[Peter Parts]

snip

The other thing to consider is HEAT. The 2005-2009 BMW 1200RT uses a NON VENTED final drive. That means the very small air space in the final drive is sealed. That sealed in air expands & compresses with heat. So, the hotter the final drive operates the higher the internal pressure on the oil & seals. In this case a thicker gear oil at operating temps MUST produce more operating heat therefore producing higher internal pressures.

Yes, not simple and intuitive like saying "thicker is better" or anything like that.

 

The problem is the human-factors of communication is back-asked. What we want to buy is oil that is more or less "constant viscosity." We want the same oil behavior hot or cold. But that isn't how the ratings go. On the contrary, to have constant viscosity, we need the most different cold and hot ratings.

 

So straight "30" is thick when cold and very thin when hot. But something like 20-50 is a bit thinner than 30 when cold (that's better) and lot thicker than 30 when hot (that's also better).

 

Sealed final drive..... I (sometimes) can't believe BMW would do something that stupid. Of course, these are the same engineers who brought us Paralever. Until about 1964, the /2 series had sealed FDs. Then they added a neat vent on top to allow pressure to escape but keep dirt out. For obvious reasons.

 

Ben

[KetoSoi]

The LS stands for Limited Slip (type of positraction). LS gear oil's claim to fame is it's ability to seep in between the limited slip clutch disks & prevent them from chattering. That Limited Slip additive used to be made from Sperm Whale oil but that was long ago before it was banned. Now it is a synthetic made additive that actually makes a good penetrating oil in it's own right.

 

Hiya DR,

 

I had spoke with a technical rep at Mobil a few years ago about this very subject. This is what I was told, all paraphrased by me...

 

Several LS additives are indeed a petroleum distillate (i.e. heavy naptha type), which from a solvent perspective make them a lot like a penetrating oil. However, the chemical properties are production formulation dependent. They can be made to dissolve rubber quickly, or be made non-reactive with various materials. There are several chemical compositions derived from other sources that can have the same basic functionality.

 

In the case for their synth 75w90 LS, he said they use a 'base friction modifier', to adjust to friction coefficient to be compatible with fiber-type (LS diff) clutch plates. The stuff is supposed to be fully compatible and non-reactive with all common automotive/powersports seal material. He went on to say: if it gets by a seal, it wont be due to a degradation via chemical reaction with the seal material, its a literal mechanical failure of the seal. A good gear oil is supposed to promote a long seal life.

 

I couldnt get him to tell me what the 'base friction modifier' was exactly, or in what quantity/ratio it was. I got the 'its proprietary' type answers.

 

For whatever thats worth....

 

 

Keto

[dirtrider]

Afternoon Keto

 

Years back the best limited slip additive going was made from sperm whale oil. I still have some on my shelf here & that stuff will almost find it's way through waxed paper. Not only did it do a great job of migrating to between tightly compressed limited slip clutch plates (some held together with upwards of 90 psi.) It also worked for lubricating (& staying) in other places that most oil's wouldn't get to due to tight clearances.

 

The old GM straight 6's would get squeaky rocker arms due to the rocker arm pocket burnishing to the rocker ball. No oil or oil additive would get into & lubricate that tight rocker to ball. You could dump in one small bottle of the old sperm whale limited slip additive & that squeak would go away while you stood there & watched it.

 

Sperm whale oil isn't used anymore (probably due to environmental concerns) & I'm not sure what the synthetic replacement is but it sure isn't as good as the old stuff for both positraction clutch chatter & as a fine lubricant.

 

Even so, the new stuff needs to have small enough molecules & some wicking ability to get in between tightly compressed limited slip clutches. Limited slip clutch packs stay pretty well compressed even when relaxed so no space for oil to circulate between the disk contact points.

 

[CSM746]

I am too lazy right now to go to the garage and look for a boss on the final drive to do this, but it would be helpful if one could tap this final drive housing to install a vent. I have a 2009RT and a 2011 GS, both purchased new. Been riding BMW exclusively since 1974. So, I am not changing brands now, but as the earlier poster similarly stated-sometimes the stupidity of this company has astonished me through the years. Like on the 2005-? models that had the drain plug on the back instead of the bottom...C'mon

[DiggerJim]

Like on the 2005-? models that had the drain plug on the back instead of the bottom...C'mon

The benefit of that arrangement is that you need to drop the unit to drain it which forces you to look at the splines & gives you an opportunity to lube those puppies up. The doofus part is the fill hole

[CSM746]

Hmmm...I can buy that...having many times having to lube splines at the 25K mark along the way. Good point, but in my case I change my final drive and transmission fluid more often than that...with tire change. I know, overkill, I baby these machines.

[Guest Kakugo]

There's a Swedish firm called Cargo Oil AB which specializes in Sperm Whale Oil (SWO) substitutes.

For food industry or other applications requiring a non-toxic lubricant with deeply penetrating properties as close as possible to SWO they use modified Jojoba oil. Don't ask me the process because I have no idea how to parse through Swedish patents and, even if I were able, I do not speak a lick of Swedish language.

 

All I know is their products work like no other lubricant I've ever used. Sadly supply has completely dried up (note the firm is not only alive and kicking but expanding as well) and I am holding dear to the very last half can of their lubricant I was able to snatch.

[Albert]

Like on the 2005-? models that had the drain plug on the back instead of the bottom...C'mon

 

Actually I think this was the better arrangement. It's easier (at least in my opinion), to refill the FD from that rear facing drain hole than it is to remove the tiny plug in the back of the FD to do it. With a bottom drain plug you're pretty much forced to use that little hole in the back. Yes you do have to drop the FD for draining but I've not found that to be difficult in the least.