Best fluid for BMW 6 speed Manual?

[TheRuss]

Originally Posted By: NorWest5
Originally Posted By: dparm
Originally Posted By: TheRuss

Why do you strongly recommend not doing that mix?



Those are two vastly different fluids that are not designed to be mixed. The additive packs are not the same and could potentially clash.

API motor oils must be mixable with other motor oils. I don't believe the same applies here.


Agree. Unless your replacement fluid meets the vehicles manufacture's specs: don't use that particular brand of transmission fluid. Mixing any replacement non-spec fluid while your vehicle is still under warranty will be Russian Roulette if there is an issue with your transmission before that warranty expires. Post warranty; do what you think best.


Well my car is no longer under BMW warranty, so I'm trying to figure out what might be the best fluid for my car. Not an easy feat, it seems.

 

[TheRuss]

Originally Posted By: badtlc
Pentosin MTF2 is the proper fill for your car. It doesn't get much better than this fluid. It is the OEM fluid for less cost.

Redline MTL, even though it is a 70W-80, it about 60% THICKER than what your transmission came with. I would only run that in your car if you were going to drive it really hard.


Hi there, I'm now looking at the Pentosin - when you say it doesn't get much better than this, do you mean in terms of oil quality? Refilling with OEM fluid has its positive and negative sides. Positives are that it's specced by OEM so must be safe, negative is that it might not improve the notchiness of the gearbox (unless it'll improve just from the fluid being fresh and clean?). Also, I thought the OEM fill for my car was an ATF?

Lastly, is that really correct that the Redline MTL is 60% thicker than the standard fluid? Seems a lot for a 70W80...

Edit - when you say you'd only run the MTL if I was going to drive it really hard - I assume you mean really hard all the time - like tracking it lots? Though I suppose the Pentosin should also be fine if I drive the car hard? Being that the car will soon be running around 100bhp more than stock, and a load more torque, I just want to ensure that the transmission has the best fluid to keep it happy whilst handling this extra power.

In reality, I spend most of my time casually driving in traffic and not on full power, but I don't want to feel like I can't drive it hard because of the fluid I'm running in my transmission...

 

[badtlc]

Pentosin makes 1st rate synthetic fluids. The specs on the MTF2 are very impressive, especially for cold performance. If you weren't trying to fix something, it would be a great choice.

The BMW OEM fill is about the same viscosity as an ATF but it is not at ATF. It actually has a GL rating which means it provides EP additives to protect the MTX. ATF does not carry a GL rating and really isn't a good choice for an MTX.

If you want something more robust to protect your upgraded car, then Redline MTL would be a very good choice in my opinion. The cold specs are almost as good as the factory fluid but it will provide a bit more protection when hot. I run it in my car and love it, and as you have read, many performance oriented BMW owners run Redline MTL with great success.

 

[TheRuss]

Originally Posted By: badtlc
Pentosin makes 1st rate synthetic fluids. The specs on the MTF2 are very impressive, especially for cold performance. If you weren't trying to fix something, it would be a great choice.

The BMW OEM fill is about the same viscosity as an ATF but it is not at ATF. It actually has a GL rating which means it provides EP additives to protect the MTX. ATF does not carry a GL rating and really isn't a good choice for an MTX.

If you want something more robust to protect your upgraded car, then Redline MTL would be a very good choice in my opinion. The cold specs are almost as good as the factory fluid but it will provide a bit more protection when hot. I run it in my car and love it, and as you have read, many performance oriented BMW owners run Redline MTL with great success.


Indeed, many do - and it's a group 5 base isn't it? What about the Pentosin? I can't find any info on the quality of the base stock.

What about the Redline MTL being 60% thicker than the OEM fluid, as mentioned earlier in this thread? I don't want to ruin my mpg and whp if it's far too thick, or should it not make any real difference in practice?

 

[badtlc]

Originally Posted By: TheRuss
]

Indeed, many do - and it's a group 5 base isn't it? What about the Pentosin? I can't find any info on the quality of the base stock.

What about the Redline MTL being 60% thicker than the OEM fluid, as mentioned earlier in this thread? I don't want to ruin my mpg and whp if it's far too thick, or should it not make any real difference in practice?


Pentosin is a full synethic, even over seas. It is either a Grp IV or V basestock. Not sure which.

Redline MTL (70W-80) is thicker at around 10.3 cSt @100C compared to Pentosin's ~6.3 cSt @100C. Technically, even though Pentosin is thinner at all temps, they categorize it as a 75W-80. They are both realtively thin fluids compared to the more common MTF 75W-90 grade. Redline MTL might hurt MPGs a bit, but i'm guessing you'd have to have a very light foot to notice the change.

 

[TheRuss]

Hmm, indeed ~4 cSt @ 100C does seem a pretty big difference. How do they manage to categorise both fluids under such similar grades with that sort've difference?!

I'm really not sure what to go for. The UK is mostly cold - we're only just seeing warm temps now after seemingly having a 6 month winter of temps no higher than 10C, so I'm not sure the MTL would be the best in these conditions, but likewise I like the idea of extra protection considering I'm working the transmission harder.

I guess the MTL is probably a good idea, as I can always go careful in cold temps, and from what I've heard it is still pretty decent in the cold.

On the other hand, the Pentosin will potentially offer better mpg and lower transmission losses, as well as better cold weather shifting, but will the "protection" really be insufficient under full load?

 

[NorWest5]

10 degrees C here is a warm spring day.

Something to remember BMW does not make lubricants, they only approve them or not for use in the vehicles they make. These fluids are developed using petro chemical technology with the intention that they do the job and are long-lived.

 

[KenO]

I'd run MTL, but you won't go wrong by mixing them either. It's been done a million times. Try the straight MTL. if you don't like the cold shifting properties - dump some out and replace with D4 or D6.

 

[JHZR2]

Originally Posted By: TheRuss


Indeed, many do - and it's a group 5 base isn't it? What about the Pentosin? I can't find any info on the quality of the base stock.

What about the Redline MTL being 60% thicker than the OEM fluid, as mentioned earlier in this thread? I don't want to ruin my mpg and whp if it's far too thick, or should it not make any real difference in practice?


I highly doubt that redline or any other fluid is majority Grp V. Maybe a small amount for certain properties; but it must also be balanced for seal swell as ester may overswell certain seals.

Im not seeing a good reason to go to MTL. Im not a believer in that fluid versus similar fluids from other manufacturers, but I also believe that a well additized fluid of the correct viscosity will offer superb performance, and a shear-stable fluid that is still an ATF viscosity but a bit thicker than the OEM MT-3 fluid is the best compromise if you insist on going heavier, especially in your climate.

 

[TheRuss]

Originally Posted By: JHZR2
Originally Posted By: TheRuss


Indeed, many do - and it's a group 5 base isn't it? What about the Pentosin? I can't find any info on the quality of the base stock.

What about the Redline MTL being 60% thicker than the OEM fluid, as mentioned earlier in this thread? I don't want to ruin my mpg and whp if it's far too thick, or should it not make any real difference in practice?


I highly doubt that redline or any other fluid is majority Grp V. Maybe a small amount for certain properties; but it must also be balanced for seal swell as ester may overswell certain seals.

Im not seeing a good reason to go to MTL. Im not a believer in that fluid versus similar fluids from other manufacturers, but I also believe that a well additized fluid of the correct viscosity will offer superb performance, and a shear-stable fluid that is still an ATF viscosity but a bit thicker than the OEM MT-3 fluid is the best compromise if you insist on going heavier, especially in your climate.


2 questions:

1.) Why don't you like the MTL vs other similar fluids? It has a good reputation in the BMW scene, plus other marques, too. I believe it's a group IV/V fluid.


2.) Based on what you said at the end there, what would be your recommendation? I agree entirely - if I could find something that is a bit thicker once warmed up, but is just as good when cold, that'd be ideal. I just need to find that fluid, and it needs to be a quality fluid.

 

[JHZR2]

MTL does feel good at the start. But Ive always had issues with it retaining the shift feel for the long run. Shift quality especially in colder weather after 10k miles more or less starts to degrade. For a daily driver, this is unacceptable. I went to AMsoil MTF, which is a 5w-30 type MTF, and havent looked back.

Otherwise Id go with a heavier yet shear stable ATF type lube, or, if you know enough about the OE MTF, I would still consider that.

Lifetime may not be the best thing, and having a bit more viscosity may be slightly useful, but if the level of additization is correct for an MT, and the fluid will be proactively changedan OE fluid (like the pentosin mentioned) is a great option, and will surely retain shift feel and quality, or improve upon it.

I look at this much like when some engines went to 5w-20 oils... Lots of doom and gloom, yet engines are running very long times without issues, using the right oil.

There is nothing wrong with the BMW fluid, or the pentosin fluid, that makes them not quality products... If BMW specced dexron III, I might be rethinking it. But with a purpose-suited MTF, IMO youre good. Unless you know for a fact that the additization isnt up to snuff or something...

 

[TheRuss]

Nah, I know nothing. I'm literally here to learn. Problem is, everybody is suggesting different, so being that I know nothing, it's proving difficult to pick out all the facts.

So far, I'm thinking that I want to avoid ATFs because they might not have the right additives to keep my manual transmission happy in the long term.

Whether mixing an ATF with the MTL would fix that issue, whilst offering smoother shifting in all temps, I dunno. That's what my oil supplier has suggested, but I don't understand how the two fluids would mix and what the effects would actually be. All they can offer me is that they've suggested it to people before and never had any issues.

For me, that's not a good enough endorsement. I could leave my manky old oil in the tranny until 100k and not have any issues, so the fact that a certain blend doesn't cause transmission detonation doesn't necessarily mean it's good, just that it isn't massively harmful.

At the moment I'm torn between Redline MTL, the Pentosin (if I can even get hold of it), and a D6/MTL blend.

What I wonder is why Redline haven't blended D6 and MTL themselves and sold it, if it works well together. "New MTL cold-shift" or something. If it was the bees knees and offered the best of both worlds then they'd have cornered the BMW niche.

That's what makes me wonder if it's a good idea.

 

[badtlc]

Originally Posted By: TheRuss
What I wonder is why Redline haven't blended D6 and MTL themselves and sold it, if it works well together. "New MTL cold-shift" or something. If it was the bees knees and offered the best of both worlds then they'd have cornered the BMW niche.

That's what makes me wonder if it's a good idea.


That is what Redline D4 is. Redline D4 is an ATF that also carries a GL-4 rating for use in an MTX just like D6. Its viscosity is around 7.3 cSt @100c. MTL is ~10.3. D6 is approximately 6.4 cSt @ 100C. That is a narrow range as it is. There really isn't any point is mixing them. Just pick the viscosity you want.

D6 is going to be a very close match to your OEM, but possibly cheaper. If you want to stick to OEM viscosity but can't afford OEM or Pentosin, it is a good choice. If you want more protection, step up to D4 or MTL.

Redline fluids are supposed to be very shear stable.

 

[KenO]

FWIW, I've seen MTL 'fix' work, crunchy BMW transmissions. First-hand knowledge.

 

[badtlc]

Originally Posted By: KenO
FWIW, I've seen MTL 'fix' work, crunchy BMW transmissions. First-hand knowledge.


I'd like to make sure I understand what you are saying. Are you saying that switching to MTL made crunchy BMW transmissions shift smoother?

 

[KenO]

Originally Posted By: badtlc
Originally Posted By: KenO
FWIW, I've seen MTL 'fix' work, crunchy BMW transmissions. First-hand knowledge.


I'd like to make sure I understand what you are saying. Are you saying that switching to MTL made crunchy BMW transmissions shift smoother?



I'm saying switching to MTL made actual crunchy transmissions (transmissions that made noise, ground, etc. when shifting) got better or disappeared entirely. Hence why it's SO well revered in BMWland. My past E36 325is that I just got rid of - great example. Drained the ATF< replaced with MTL. When I bought it with ~230k, upshifts would grind into 2nd, and sometimes 3rd unless you revmatched, and downshifts to 2nd and 1st unless you rev-matched. Post - MTL, maybe 2 weeks later, the 3rd gear upshift was completely gone, and the rest were significantly better than they were. I ended up just rev-matching this trans for every shift, but WOT redline shifts - it never made noise :shrug

 

[TheRuss]

Originally Posted By: badtlc
Originally Posted By: TheRuss
What I wonder is why Redline haven't blended D6 and MTL themselves and sold it, if it works well together. "New MTL cold-shift" or something. If it was the bees knees and offered the best of both worlds then they'd have cornered the BMW niche.

That's what makes me wonder if it's a good idea.


That is what Redline D4 is. Redline D4 is an ATF that also carries a GL-4 rating for use in an MTX just like D6. Its viscosity is around 7.3 cSt @100c. MTL is ~10.3. D6 is approximately 6.4 cSt @ 100C. That is a narrow range as it is. There really isn't any point is mixing them. Just pick the viscosity you want.

D6 is going to be a very close match to your OEM, but possibly cheaper. If you want to stick to OEM viscosity but can't afford OEM or Pentosin, it is a good choice. If you want more protection, step up to D4 or MTL.

Redline fluids are supposed to be very shear stable.


I thought that D4, being an ATF, wouldn't lubricate as well as something like MTL because it was designed for autos?

 

[badtlc]

Originally Posted By: TheRuss

I thought that D4, being an ATF, wouldn't lubricate as well as something like MTL because it was designed for autos?


Redline's ATFs aren't normal ATFs. Redline blends them so that they provide GL-4 protection for MTXs. They should work fine in an MTX requiring those viscosities.

 

[JHZR2]

Originally Posted By: TheRuss
Originally Posted By: badtlc
Originally Posted By: TheRuss
What I wonder is why Redline haven't blended D6 and MTL themselves and sold it, if it works well together. "New MTL cold-shift" or something. If it was the bees knees and offered the best of both worlds then they'd have cornered the BMW niche.

That's what makes me wonder if it's a good idea.


That is what Redline D4 is. Redline D4 is an ATF that also carries a GL-4 rating for use in an MTX just like D6. Its viscosity is around 7.3 cSt @100c. MTL is ~10.3. D6 is approximately 6.4 cSt @ 100C. That is a narrow range as it is. There really isn't any point is mixing them. Just pick the viscosity you want.

D6 is going to be a very close match to your OEM, but possibly cheaper. If you want to stick to OEM viscosity but can't afford OEM or Pentosin, it is a good choice. If you want more protection, step up to D4 or MTL.

Redline fluids are supposed to be very shear stable.


I thought that D4, being an ATF, wouldn't lubricate as well as something like MTL because it was designed for autos?


Its all about the add packs. That's the thing. If BMW specified Dexron ATF, I would agree that it may not be optimal. That is why the gearbox in my 318i, which specifies good old ATF gets an alternate fluid.

But a gearbox that specifies a purpose-specific low viscosity MTF that has the viscosity of ATF is sood to go. And using a fluid like the redline D4 or BMW or Pentosin fluids is perfectly fine.

Heck, there are tons of MTs that have gone hundreds of thousands of miles on plain old ATF too!

I wouldnt think twice about it. My ONLY issue is that since even GM states that Dex VI is not suitable for MTs, IF the BMW fluid is less viscous than the D4 ATF or equivalent fluid, you may be better off running the BMW/Pentosin fluid, which has the right viscosity and protection levels inherent. D6 may cause issues of another type.

Youre proactive and will change the fluid out. You shouldnt be afraid of a low viscosity fluid that is properly additized.

 

[TheRuss]

Ok, now you've lost me!

So because BMW state an ATF should be used, you've gone for something else, and because mine says MTF I should go for an ATF? You've lost me!