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synthetic gear oil / recommendations


newcastle

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75w140 GL5 synthetic in the gearbox and 75w90 synthetic in the rear end.

Certainly noticed the smoother shifting with the 75w140 in the gearbox thumbsup.gif

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Bill_Walker

Didn't we all answer this just a week or two ago?

 

Anyway, I use the BMW 75w140 synthetic. It's still under warranty. I figure they're less likely to complain if I use their stuff.

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I personally can't really see how using synthetic oil in the transmission could matter much. In all but the earliest model oilhead transmissions the bearings are sealed so they won't know or care what is in there, and the gearsets themselves are pretty hefty and any standard gear oil is probably more than adequate. I've never heard of oilhead transmission gears failing due to any kind of lubrication failure (when recommended lubricants were used), in fact I've never seen any that showed any significant wear regardless of mileage. Also, from what I can tell the clunkiness of the oilhead transmission seems to have mostly to do with the shift change mechanism itself and the wide spacing of the gear dogs and I can't see how oil formulation would help this much. I've tried standard and synthetic in various weights and have never been able to tell much a difference myself, or at least if you swapped one or another type of oil in there and didn't tell me which it was I doubt that I could identify it. (BTW I'm not trying to rustle feathers or say that anyone else is imagining anything, only that I personally couldn't tell a difference.)

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I thought the bearings were conventional (non-sealed) through 2004?
No, sealed caged bearings were used from 1997 on.
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I personally can't really see how using synthetic oil in the transmission could matter much.

 

When I had an '01 K1200RS, I changed the transmission fluid from Dino to synth (Redline Heavy Duty Shockproof...looks exactly like Pepto Bismol... lmao.gif). It made a HUGE difference in the transmission "feel"...less "clunk" and much smoother shifts. clap.gif

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I personally can't really see how using synthetic oil in the transmission could matter much. In all but the earliest model oilhead transmissions the bearings are sealed so they won't know or care what is in there, and the gearsets themselves are pretty hefty and any standard gear oil is probably more than adequate. I've never heard of oilhead transmission gears failing due to any kind of lubrication failure (when recommended lubricants were used), in fact I've never seen any that showed any significant wear regardless of mileage. Also, from what I can tell the clunkiness of the oilhead transmission seems to have mostly to do with the shift change mechanism itself and the wide spacing of the gear dogs and I can't see how oil formulation would help this much. I've tried standard and synthetic in various weights and have never been able to tell much a difference myself, or at least if you swapped one or another type of oil in there and didn't tell me which it was I doubt that I could identify it. (BTW I'm not trying to rustle feathers or say that anyone else is imagining anything, only that I personally couldn't tell a difference.)

 

Seth, I agree with you on the sealed bearings so that end of it is mute as far as oil lubricity goes.. Same with gear wear as the BMW Getrag trans is way over designed gear set wise..

 

Having run different types or gear oil bases/viscosities (synthetic/Dino/mix) in both my 1100 & 1150 I can say from experience that you sure can tell the difference in the various gear oil bases.. Can’t say it just a Dino/Synthetic thing though but more than likely the combination of different viscosity rating of the various gear oils along with base oil differences & friction modifier package differences .. It also depends on what effect/difference you are looking at..

 

There even seems to be a difference between transmissions on what gear oil subjectively feels best..

 

On my 5spd 1100 there was real improvement noted on shifting feel, positive gear changes, & neutral gear rattle when I went from 80W90 Dino to the Red Line Heavy “shock proof” (that’s something like 80W140 rated with an equivalent 250 rating at high temp.. The good shifting characteristic stayed with the bike for the full gear oil change interval but the neutral gear rattle would start to degrade at about 4000 miles.. In using Mobil 1 75W140 synthetic in the same bike the neutral gear rattle was not good from the get go & really noticeable at hot trans curb idle.. Gear changes were good on all ranges except 1-2 as the 1-2 shift became very notchy feeling.. The general trans noise was also notably degraded riding down the road (especially very hot).. Basically I ended up using the Red Line Heavy “shock proof” in the 1100 as that subjectively & noise wise seemed best between the few gear oil’s that I evaluated..

 

Next came my 1150RT.. The first gear oil I used in that gear box was 80W90 & the trans had very objectionable neutral gear rattle, rather notchy shifting, very sluggish cold weather shifting.. I then switched over to the Red Line Heavy “shock proof” the basic shift feel immediately improved, hot neutral gear rattle improved but still prevalent, kind of poor neutral to 1st engagement (especially cold).. I figured it was just the 6 speed attributes so kind of lived with it for quite a few thousand miles.. As the miles went by I did a few changes to the same Red Line Heavy but the 1st to 2nd shift got worse & worse with hang shifts going from 1st to 2nd & more & more missed 1-2 upshifts (downshifts were still very good though).. I hadn’t tried the Mobil 1_ 75W140 in that bike yet so I drained the Red Line & installed the Mobil 1.. It took a few hundred miles for the Mobil 1 to wash the Red Line from the trans sliders but in a short time the 1st to 2nd shift felt much improved with almost no missed 1-2 upshifts (the few I missed were probably me using a lazy foot) .. I have had that Mobil 1 in the gear box for probably 5 thousand miles now & the down side seems to be it has made the gear box general road speed noise louder, allows pretty severe neutral gear rattle, allowed a little more gear whine in 6th gear.. The upside is the 1-2 upshift is noticeably improved, neutral to 1st engagement is noticeably improved, cool weather clutch-engaged fast idle is slightly higher..

 

Two different bikes with two different transmissions & they subjectively liked different trans gear oils.. I know not much of a sample rate here so what I suggest is TRY different gear oil types/viscosities to see if any one makes your bike trans act closer to what you like..

 

Twisty

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Well I must admit that I've never tried any of the miracle fluids (Redline, Amsoil, etc.) so perhaps there may be a difference there, but in my experience plain 'ol 80W-90 works just fine. A BMW gearbox is what it is and beyond making sure that there are no internal problems it's best to treat it like a recalcitrant child... stop giving it attention and the problem diminishes... grin.gif

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I thought I read on here that people have claimed failures due to some of the synthetics. I recall it being the 75w140.

 

I'd like to use synthetics when i do the gearboxes in 2K miles.

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I thought I read on here that people have claimed failures due to some of the synthetics. I recall it being the 75w140.
The only one I can recall is Scott's (SWB) failure but that one was kind of bizarre and there was no direct evidence that it was caused by a lubricant failure, other than a possibly coincidental proximity in time. The gearsets in the oilhead transmission are pretty meaty... I can't imagine much damaging them beyond perhaps no lubrication...

 

I think you are perfectly safe in using a synthetic, although as I mentioned I don't think that they are particularly valuable in this application... except for perhaps on a hexhead final drive where the owner insists on believing in BMW's 'lifetime' fill concept and intends on leaving the oil in there forever.

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I thought I read on here that people have claimed failures due to some of the synthetics. I recall it being the 75w140.
The only one I can recall is Scott's (SWB) failure but that one was kind of bizarre and there was no direct evidence that it was caused by a lubricant failure, other than a possibly coincidental proximity in time. The gearsets in the oilhead transmission are pretty meaty... I can't imagine much damaging them beyond perhaps no lubrication...

 

I think you are perfectly safe in using a synthetic, although as I mentioned I don't think that they are particularly valuable in this application... except for perhaps on a hexhead final drive where the owner insists on believing in BMW's 'lifetime' fill concept and intends on leaving the oil in there forever.

 

The main reasons I would want synthetic is its ability to withstand higher temps and lower operating temps.

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I thought I read on here that people have claimed failures due to some of the synthetics. I recall it being the 75w140.

 

I'd like to use synthetics when i do the gearboxes in 2K miles.

 

Perry, as mentioned above there is probably no particular gain in gear life or bearing life (trans has sealed & clean bearings).. The trans gear sets are for the most part straight set teeth so there is not even much of a need for a GL-5 type gear oil (even though BMW specs a GL-5 gear oil) ..

 

In my estimation the main gain from synthetic gear oil is a little better flowability in extreme cold ride away & possibly a little better heat handling ability due the catalytic converter being right below the trans..

The other advantage (in my opinion) is the superior additive package in most uplevel synthetic gear oils but that same additive package is probably present in uplevel Dino gear oil’s also.. Some of the better additives can aid the sliding shifting collars move easier during the shift & the usual thinner base stock of a good synthetic can allow the free floating gears spin with less drag on the shafts so the shift dogs can find home easier on the shift (BMW trans gears have slightly less slop between the sliding dog teeth & engagement slots so anything that impedes match up will hinder sifting).. On the other hand manual transmissions lubricate from gear oil being carried by the spinning gear sets & as a rule thinner synthetic gear oil has less gear tooth cling than thicker based Dino gear oil.. Noise wise you are probably better off using a nice thick based tooth cushioning Dino based gear oil.. Shifting wise you are probably better off using a slipperier thinner based uplevel synthetic based gear oil.. (thick & clingy is best for tooth contact noise with thin & slippery being better for shifting ease)..

 

Twisty

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noise wise you are probably better off using a nice thick based tooth cushioning Dino based gear oil.. Shifting wise you are probably better off using a slipperier thinner based uplevel synthetic based gear oil..

 

This is why I'm not sure what I want to go with due to your statement above. I was reading the post you had a few up from this one. I dont want noise, but I was smoother shifting.

 

What is your opinion about rear drive oil?

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If I can ask, does anyone know of the 'Moly' additve that some have reccomended? I have looked and found companies like Dow Corning offering product, anybody else? This would be a good additve to a good 75/140 Synth perhaps...

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If I can ask, does anyone know of the 'Moly' additve that some have reccomended? I have looked and found companies like Dow Corning offering product, anybody else? This would be a good additve to a good 75/140 Synth perhaps...

 

Ford uses an additive in their rear diffs. I suspect it is moly. It is sold at the parts counter.

 

I have Moly powder at work....I wonder if I can mix it with gear oil.

 

My father has used a moly product sold in quart containers for about 15 years now. I'll ask him what he uses and where to get it.

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noise wise you are probably better off using a nice thick based tooth cushioning Dino based gear oil.. Shifting wise you are probably better off using a slipperier thinner based uplevel synthetic based gear oil..

 

This is why I'm not sure what I want to go with due to your statement above. I was reading the post you had a few up from this one. I dont want noise, but I was smoother shifting.

 

What is your opinion about rear drive oil?

 

Perry, I don’t use anything special in the final drive unit.. I just use 80W90 Dino GL-5 gear lube.. Many reasons for the above..

 

First & foremost is there is just nothing in that final drive that needs a synthetic gear oil.. It isn’t a true Hypoid gear set so needs nothing special there,, there is no differential in the rear drive so nothing special needed there.. There have been no reports of rear gear failures so nothing special (like added moly) needed to protect the ring & pinion..

 

Now the large bearing in the final drive is another story as those have a pretty substantial failure record.. In my opinion synthetic gear oil does nothing to protect the deep groove bearing & in some cases could add to it’s failure record.. Some of those gear oil additive packages can contain extra Molybdenum & that can build up on the bearing balls or in the groove of the race & cause bearing issues (the auto industry has had some moly related ball bearing failures)

 

What I do is just use standard Dino 80W90 then change the rear drive oil with every engine oil change.. That allows looking at the rear drain plug magnet for metal shads & looking at the gear oil color & condition.. The rear drive only holds a small amount of gear oil so it is cheap insurance to drain it with every engine oil change.. Changing the gear oil often will not stop a bearing failure but can give an early warning of impending bearing failure..

 

Twisty

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If I can ask, does anyone know of the 'Moly' additve that some have reccomended? I have looked and found companies like Dow Corning offering product, anybody else? This would be a good additve to a good 75/140 Synth perhaps...

 

Rob, why do you think you need EXTRA moly (molybdenum) ? Are you failing rear ring & pinions? Moly is a high scuff load additive (mainly for high load helical gear teeth protection)..

 

Twisty

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In my opinion synthetic gear oil does nothing to protect the deep groove bearing & in some cases could add to it’s failure record

 

I think that is the failure I was referring to in an earlier post using synthetic.

 

 

Some of those gear oil additive packages can contain extra Molybdenum & that can build up on the bearing balls or in the groove of the race & cause bearing issues (the auto industry has had some moly related ball bearing failures)

 

I didn't know that.

 

 

Thanks for the info / opinions.

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SteveHebert

When we rebuilt the transmission in my 81 R100RS, we refilled with Royal Purple. We also put that in the final drive. It made a big difference as well. It is pricey, but seems to be worth it.

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