[VisualEcho]

Originally Posted by F87source

Yup I noticed the same and that was with stock fluid at around 9k km. I could only imagine how much better dctf feels. I'll be getting that for my next transmission fluid flush too.

My car was sold in December of 2017 and has 20K on the clock at the moment. I was thinking of changing the fluid now, but I'll be just out of warranty. You recommend the Redline instead of the BMW fluid?

I never track my car, and will only be driving about 5,000 miles a year. That puts me at 20K every 4 years, which I thought might be a good interval. Do you agree?

[F87source]

Originally Posted by VisualEcho

My car was sold in December of 2017 and has 20K on the clock at the moment. I was thinking of changing the fluid now, but I'll be just out of warranty. You recommend the Redline instead of the BMW fluid?

I never track my car, and will only be driving about 5,000 miles a year. That puts me at 20K every 4 years, which I thought might be a good interval. Do you agree?

Yeah I was going to get redline dctf over mtf as well, but the lead time was too long. But I do believe the redline fluid is better overall as it's heavy in Pao and esters so it should provide higher shear strength and better protection, this should also makes shifts smoother. However esters and paos oxidize quickly so I do not know if they'd make it that long with that many miles. You might need a UOA to check to see if 4 years at 20k miles is ok.


Also I got your pm but it'll take me some time to reply.

[David.m]

Some positive feedback for the Redline DCTF fluid.

Around a month ago while I was removing the CDV I changed MT fluid & used the Redline DCTF as BMW Australia didn't have any stock of the oem MTF-LT-5. I had only replaced the MT fluid with oem 20K km earlier (@66K km) but thought that while I had the undertray off doing the clutch I'll do the transmission again.

With the Redline I won't say that shifting is noticeably smoother but a definite improvement is going into 1st, it is silky smooth every time without fail. Previously it was always a little notchy and on occasion (eg stopped at lights in neutral) it would resist engaging 1st so I'd release/depress the clutch again to engage 1st (an alternate was to select 2nd then 1st).

I couldn't believe it when the dealer told me it would be a 4month wait for the oem fluid to ship from Germany, seems they did me a favour

[F87source]

Originally Posted by David.m

Some positive feedback for the Redline DCTF fluid.

Around a month ago while I was removing the CDV I changed MT fluid & used the Redline DCTF as BMW Australia didn't have any stock of the oem MTF-LT-5. I had only replaced the MT fluid with oem 20K km earlier (@66K km) but thought that while I had the undertray off doing the clutch I'll do the transmission again.

With the Redline I won't say that shifting is noticeably smoother but a definite improvement is going into 1st, it is silky smooth every time without fail. Previously it was always a little notchy and on occasion (eg stopped at lights in neutral) it would resist engaging 1st so I'd release/depress the clutch again to engage 1st (an alternate was to select 2nd then 1st).

I couldn't believe it when the dealer told me it would be a 4month wait for the oem fluid to ship from Germany, seems they did me a favour

Good to hear!

For me I noticed a huge difference just going to new stock fluids, so imo it's definitely worth it just to flush the old fluid out even with stock fluid. I'd say redline would offer even better feel.

But note with the high ester content in this oil it'll oxidize quicker than the stock stuff, so change it out more frequently.

[nioh_lbbm2]

Originally Posted by F87source

Good to hear!

For me I noticed a huge difference just going to new stock fluids, so imo it's definitely worth it just to flush the old fluid out even with stock fluid. I'd say redline would offer even better feel.

But note with the high ester content in this oil it'll oxidize quicker than the stock stuff, so change it out more frequently.

+1 to definite improvement with new stock fluid.
Just had mine done at roughly 40k miles and the smoothness felt was almost night and day. A lot of the notchiness was reduced too

[F87source]

Originally Posted by nioh_lbbm2

+1 to definite improvement with new stock fluid.
Just had mine done at roughly 40k miles and the smoothness felt was almost night and day. A lot of the notchiness was reduced too

Goes to show "lifetime" fluids are totally BS.

[nioh_lbbm2]

Originally Posted by F87source

Goes to show "lifetime" fluids are totally BS.

Yup! Also had diff fluid changed as well.

Next up prob coolant at 50k miles. Another supposed "lifetime" fluid

[F87source]

Originally Posted by nioh_lbbm2

Yup! Also had diff fluid changed as well.

Next up prob coolant at 50k miles. Another supposed "lifetime" fluid

Yup I do diff oil every 4 years, because our diffs are sensitive and have been recalled for excessive clutch wear.

I also do coolant every 4 years too, the gean company that makes coolant for bmw reports a 5 year max life span for coolant iirc. When I did my coolant I didn't really notice any issue withtbhe factory fill after 4 years though. But it was really cheap when you buy the gallon of concentrated antifreeze and just mix it with distilled water.

The only issue with the coolant job is it's insanely messy as you just pull the hose off the water pump and let it blast everywhere, and also you have to remove alot of stuff to get to the water pump.

[PackPride85]

Originally Posted by F87source

Yup I do diff oil every 4 years, because our diffs are sensitive and have been recalled for excessive clutch wear.

I also do coolant every 4 years too, the gean company that makes coolant for bmw reports a 5 year max life span for coolant iirc. When I did my coolant I didn't really notice any issue withtbhe factory fill after 4 years though. But it was really cheap when you buy the gallon of concentrated antifreeze and just mix it with distilled water.

The only issue with the coolant job is it's insanely messy as you just pull the hose off the water pump and let it blast everywhere, and also you have to remove alot of stuff to get to the water pump.

How did you do the refill on the coolant? Service manual says to use that vacuum filling device that most newer cars seem to require, then the standard bleeding procedure by activating the water pump with the car off to bleed.

[F87source]

Originally Posted by PackPride85

How did you do the refill on the coolant? Service manual says to use that vacuum filling device that most newer cars seem to require, then the standard bleeding procedure by activating the water pump with the car off to bleed.

Excellent question, technically if you want to do it right you should buy the vaccum bleeder tool, FCP euro sells a decent unit you can use. Then you need 2 buckets and an air compressor. BMW DIY Guy has a really good youtube video on how to do this bleed.


Now what I did was just bleed using the built in bleeding procedure, and here is why I believe it is acceptable.

1) The way the coolant expansion tank sits, it is the highest point in the loop - if you fill it all the way to the middle point (the seam) and above. This means as you fill the loop all air bubbles should be force up and out through the expansion tank. Now this might not always be the case on tight bendy loops but the reasons below ensure this happens on our n55 engine.

2) The block is tilted, and it fills from the bottom side up. The outlet for the coolant is then the high point and since it is tilted the block will fill all the way up before coolant spills out, this is an ingenious design by bmw to ensure the water jacket around the cylinders are always full. The head will also fill up too because the drain hose is a bit lower than the main oulet port for the block, and this goes to the thermostat which goes to the water pump aka the lowest part of the loop. This will eventually fill up and back up to the head and force air bubbles out via the main coolant exit from the block via the oil pump housing. This leads to the radiator.

3) The coolant will then fill the radiator top down, this ensures that the radiator is full and there will not be air pockets at the top. The radiator hose leading to the radiator has an expansion line that acts as a "air pocket remover" since this is the high point between the radiator and engine block air bubbles like to accumulate there, and the over flow hose siphons air bubbles out and dumps it into the coolant expansion tank. again another ingenious design by bmw. This is why this hose goes to the expansion tank and is above the water level and air doesn't use this path as an entry way back into the coolant loop, because as coolant flows it is pushed into this hose one way and into the coolant expansion tank, this also take bubbles from the highest point in the loop (aside from the expansion tank) and dumps it into the block.

overall you essentially fill the tank, it goes directly to the water pump and you fill the loop both ways (in the direction of normal coolant flow and the opposite direction) from the bottom up. This fills the block completely then as the water level rises any air bubbles are forced to the next highest point in the block aka the expansion hose where it siphons all the air out and into the expansion tank - super smart design by bmw. Literally just by filling the loop you bleed nearly all the air out of the system, and when you run the built in bleed 20x times (like I did) the coolant will only drop for the first run or two then stay steady. But make sure if you do it this way you run the built in bleed method alot.

This might be super confusing if you didn't look at coolant flow diagrams on the n55 technical document and pull apart the cooling system yourself, but if you do it will make sense. Also sorry if my explanation is confusing I don't know how to word it better.



Then after doing this method I logged coolant temps, and cylinder timing to seeing if any knock occured due to a cylinder being hotter than another (due to an air pocket in the water jacket), and everything turned out fine temps are rock solid at 94C in sport+ which is what they were from before.

Also I talked to a few dealership master techs and indy shops, they all do the built in bleed method a few times when flushing coolant on the N5X powered cars. The only time they use the vaccum bleeder is when an s55 show up, because of the mechanical water pumps and the lack of built in bleeding.

[PackPride85]

Originally Posted by F87source

Excellent question, technically if you want to do it right you should buy the vaccum bleeder tool, FCP euro sells a decent unit you can use. Then you need 2 buckets and an air compressor. BMW DIY Guy has a really good youtube video on how to do this bleed.


Now what I did was just bleed using the built in bleeding procedure, and here is why I believe it is acceptable.

1) The way the coolant expansion tank sits, it is the highest point in the loop - if you fill it all the way to the middle point (the seam) and above. This means as you fill the loop all air bubbles should be force up and out through the expansion tank. Now this might not always be the case on tight bendy loops but the reasons below ensure this happens on our n55 engine.

2) The block is tilted, and it fills from the bottom side up. The outlet for the coolant is then the high point and since it is tilted the block will fill all the way up before coolant spills out, this is an ingenious design by bmw to ensure the water jacket around the cylinders are always full. The head will also fill up too because the drain hose is a bit lower than the main oulet port for the block, and this goes to the thermostat which goes to the water pump aka the lowest part of the loop. This will eventually fill up and back up to the head and force air bubbles out via the main coolant exit from the block via the oil pump housing. This leads to the radiator.

3) The coolant will then fill the radiator top down, this ensures that the radiator is full and there will not be air pockets at the top. The radiator hose leading to the radiator has an expansion line that acts as a "air pocket remover" since this is the high point between the radiator and engine block air bubbles like to accumulate there, and the over flow hose siphons air bubbles out and dumps it into the coolant expansion tank. again another ingenious design by bmw. This is why this hose goes to the expansion tank and is above the water level and air doesn't use this path as an entry way back into the coolant loop, because as coolant flows it is pushed into this hose one way and into the coolant expansion tank, this also take bubbles from the highest point in the loop (aside from the expansion tank) and dumps it into the block.

overall you essentially fill the tank, it goes directly to the water pump and you fill the loop both ways (in the direction of normal coolant flow and the opposite direction) from the bottom up. This fills the block completely then as the water level rises any air bubbles are forced to the next highest point in the block aka the expansion hose where it siphons all the air out and into the expansion tank - super smart design by bmw. Literally just by filling the loop you bleed nearly all the air out of the system, and when you run the built in bleed 20x times (like I did) the coolant will only drop for the first run or two then stay steady. But make sure if you do it this way you run the built in bleed method alot.

This might be super confusing if you didn't look at coolant flow diagrams on the n55 technical document and pull apart the cooling system yourself, but if you do it will make sense. Also sorry if my explanation is confusing I don't know how to word it better.



Then after doing this method I logged coolant temps, and cylinder timing to seeing if any knock occured due to a cylinder being hotter than another (due to an air pocket in the water jacket), and everything turned out fine temps are rock solid at 94C in sport+ which is what they were from before.

Also I talked to a few dealership master techs and indy shops, they all do the built in bleed method a few times when flushing coolant on the N5X powered cars. The only time they use the vaccum bleeder is when an s55 show up, because of the mechanical water pumps and the lack of built in bleeding.

Thanks for the write up. I wish they had a better way to drain than pulling the water pump hose off like that. Looks messy lol.

[David.m]

Originally Posted by PackPride85

Thanks for the write up. I wish they had a better way to drain than pulling the water pump hose off like that. Looks messy lol.

Thought I read somewhere that you can drain coolant at the aux side radiator, easier to access and capture the fluid?

[F87source]

Originally Posted by PackPride85

Thanks for the write up. I wish they had a better way to drain than pulling the water pump hose off like that. Looks messy lol.

Yeah it was terrible, I was soaked and it went all over the garage floor.

[F87source]

Originally Posted by David.m

Thought I read somewhere that you can drain coolant at the aux side radiator, easier to access and capture the fluid?

Maybe, but that's alot of work to pull the fender liner and disconnect that hose. But even then it wouldn't empty the whole loop.


Just make sure you guys really top off that expansion tank to the absolute top (so you have physics on your side to help push out all the air) and then run the bleed cycle a crap ton to really purge any air. Use a battery charger if you have one. My CTEK MUS7002 on supply mode is able to generate like 7 amps (helps a bit but IIRC the car can pull 20-40 amps just sitting with the head lights on in accessory mode), and I turned off the idrive display to help out. I was able to bleed it like 16-20 times before I felt satisfied (fluid levels stopped dropping like after 2-3 bleeds iirc) and there was zero voltage issues.

[vrooooom]

Changed my 6MT's fluid today w/ RedLine. Didn't noticed any improvement. If I'm to really push it, myb 5% better? Could just be in my head. I guess 3000 kms wasn't enough to cause noticeable degradation (for me anyways). Visually, it was a little cloudy. Pretty straight forward work. I did my oil change first.

[F87source]

Originally Posted by vrooooom

Changed my 6MT's fluid today w/ RedLine. Didn't noticed any improvement. If I'm to really push it, myb 5% better? Could just be in my head. I guess 3000 kms wasn't enough to cause noticeable degradation (for me anyways). Visually, it was a little cloudy. Pretty straight forward.

Mine was at like 8k and I absolutely did notice a big difference. Could be the lower mileage or car to car variences or related to time spent in each gear vs. shifting. Like I shift and downshift alot so it could contribute to more wear and particulate matter in the oil leading to a better feel upon a fluid swap.

[David.m]

Originally Posted by David.m

Some positive feedback for the Redline DCTF fluid.

Around a month ago while I was removing the CDV I changed MT fluid & used the Redline DCTF as BMW Australia didn't have any stock of the oem MTF-LT-5. I had only replaced the MT fluid with oem 20K km earlier (@66K km) but thought that while I had the undertray off doing the clutch I'll do the transmission again.

With the Redline I won't say that shifting is noticeably smoother but a definite improvement is going into 1st, it is silky smooth every time without fail. Previously it was always a little notchy and on occasion (eg stopped at lights in neutral) it would resist engaging 1st so I'd release/depress the clutch again to engage 1st (an alternate was to select 2nd then 1st).

I couldn't believe it when the dealer told me it would be a 4month wait for the oem fluid to ship from Germany, seems they did me a favour

Just further to the above, I've now done 12K km since putting the Redline DCTF in and not once has there been any resistance going into 1st when stationary. In the previous 85K km with the oem fluid this had never been the case even with fresh fluid in. It only happened say 10-20% of the time but you wouldn't wait for the lights to go green to go into 1st incase it did, now I don't give it a 2nd thought.

[F87source]

Originally Posted by David.m

Just further to the above, I've now done 12K km since putting the Redline DCTF in and not once has there been any resistance going into 1st when stationary. In the previous 85K km with the oem fluid this had never been the case even with fresh fluid in. It only happened say 10-20% of the time but you wouldn't wait for the lights to go green to go into 1st incase it did, now I don't give it a 2nd thought.

Wow that's some really good testimony, ok now I really want some redline dctf.

[MrMnM]

Hi, just reading blog. Since manual transmissions uses a high viscosity gear oil (ie 75-90W) they don’t need to be changed often. Of course with all lubricants you have to consider usage. An early initial change in case there are any metal shavings after breakin is a good idea, then if there is regular heavy use, tracktime, does a lot of short trips, or sits in a garage for a long time and one that changes temp a lot it should be changed more often ……in maybe 50,000 km? Otherwise it change be changed at long intervals >200,000km.

[F87source]

Originally Posted by MrMnM

Hi, just reading blog. Since manual transmissions uses a high viscosity gear oil (ie 75-90W) they don’t need to be changed often. Of course with all lubricants you have to consider usage. An early initial change in case there are any metal shavings after breakin is a good idea, then if there is regular heavy use, tracktime, does a lot of short trips, or sits in a garage for a long time and one that changes temp a lot it should be changed more often ……in maybe 50,000 km? Otherwise it change be changed at long intervals >200,000km.

This is incorrect because oxidation is also a factor not just useage, this is especially prevalant in ester based oils. Shearing is not a huge factor with such thick oil, but it does occur over time and again is a reason for not wanting to have incredibly long change intervals. The additives also degrade over time as well, so again long interval changes are not ideal if you want the car to last. 50k km is reasonable, 200k km is not.

[vrooooom]

I'm on the Redline and my shifts from 1st > 2nd > 3rd when really working it hard is not very smooth (lack of word to describe). Shifting quick seems to struggle but if not in a hurry (gentler), no issues. Never had issues going to 1st from neutral.

[F87source]

Originally Posted by vrooooom

I'm on the Redline and my shifts from 1st > 2nd > 3rd when really working it hard is not very smooth (lack of word to describe). Shifting quick seems to struggle but if not in a hurry (gentler), no issues. Never had issues going to 1st from neutral.

Interesting. But to me this sounds like a clutch delay valve issue not a fluid issue.