[EnerJi]

Does anyone know the recommended coolant flush interval (e.g. as specified by the Bentley manual?) My 2013's maintenance book says that coolant is "lifetime," although I know to take that with a very generous pinch of salt.

My (out of warranty w/ 70k miles) '13 335i car was at BMW recently to get the fuel pump replaced (under extended warranty for that part). The tech wrote that my coolant system 'needs attention' and put 'Coolant Flush' on the list of optional services to discuss with me, but never mentioned it (perhaps because I ended up declining some other work they recommended and letting my indy shop handle it).

The indy shop also didn't say anything about the coolant system...

[bavarianride]

To OP, the BMW blue coolant supposedly is 100k miles of change interval.

The boiling and freezing points of the coolant do not change over time, provided the mixture is maintained at 50/50 or 60/40 etc, etc.

The pH level(and hence anti-corrosion property) does change with age and miles, e.g. mine was tested around pH=7(neutral) last month, so mine was drained and filled at 52k miles for $160 at dealer.

The TIS procedure does not show flush/vacuum to evict all fluids, so in general the first change is 100k, any subsequent one is 50k.

[Broadsword]

I've been following Mike Miller's Lifetime Maintenance Schedule's recommendation of every two years.

[Billfitz]

Two years is excessive, unless you drive 25,000 miles a year. 50 to 60k miles is appropriate.
I can remember when 30k miles was common, in the days of cast iron blocks that caused rust build up in the coolant, but with aluminum blocks that doesn't happen.

[EnerJi]

Originally Posted by bavarianride

To OP, the BMW blue coolant supposedly is 100k miles of change interval.

The boiling and freezing points of the coolant do not change over time, provided the mixture is maintained at 50/50 or 60/40 etc, etc.

The pH level(and hence anti-corrosion property) does change with age and miles, e.g. mine was tested around pH=7(neutral) last month, so mine was drained and filled at 52k miles for $160 at dealer.

The TIS procedure does not show flush/vacuum to evict all fluids, so in general the first change is 100k, any subsequent one is 50k.

Thank you. Is the PH test something any Indy shop should be able to easily do? Do you happen to know what is the expected PH when new and when it is out of spec and needs to be replaced?

Thanks!

[bavarianride]

Originally Posted by EnerJi

Thank you. Is the PH test something any Indy shop should be able to easily do? Do you happen to know what is the expected PH when new and when it is out of spec and needs to be replaced?

Thanks!

pH test strips/kits(specific to coolant, or even fish tank ones from PetsMart) should work OK. There are also coolant meters on Amazon too.

BMW (dark) blue coolant undiluted is around 10-11, when mixed with diluted water(pH=7), 50/50 should be around 8.5-9. The freshly mixed 50/50 is still blue, while my 52k-old mixture was fading blue(almost clear), so the color can be a visual cue to check.

FYI, pH=7 neutral, while less than 7 is becoming acidic(and can start corroding metal/aluminum engine block)

[bavarianride]

Another point is that, not all bottled water is pH=7(e.g. Aquafina is 5 or something), so beware when refilling coolant level with water.

[F32Fleet]

It's lifetime like all other brands which use G48.

Eventually you'll have to replace the water pump and thermostat. Don't forget the coolant hoses. BMW recommends you change them at 6 or more years.

[Broadsword]

Originally Posted by F32Fleet

BMW recommends you change them at 6 or more years.

Is that in writing anywhere? Thanks!

[bavarianride]

Originally Posted by F32Fleet

It's lifetime like all other brands which use G48.

Eventually you'll have to replace the water pump and thermostat. Don't forget the coolant hoses. BMW recommends you change them at 6 or more years.

BMWNA had a thermostat recall on my N26 2.5 years ago, and I incorrectly assumed that coolant was flushed.

It turns out the invoice said 1L of coolant for top-off, and foreman at dealer confirmed that for that recall, BMWNA instructed service to recapture and reuse coolant!@#$%!

Please also send the link for BMW's recommendation for hose replacement every 6 years, as mine is getting to that point too.

[F32Fleet]

Originally Posted by Broadsword

Is that in writing anywhere? Thanks!

https://www.newtis.info/tisv2/a/en/f...lines/IEIjMkuc


Very bottom of page under "recommend"

[F32Fleet]

Originally Posted by bavarianride

BMWNA had a thermostat recall on my N26 2.5 years ago, and I incorrectly assumed that coolant was flushed.

It turns out the invoice said 1L of coolant for top-off, and foreman at dealer confirmed that for that recall, BMWNA instructed service to recapture and reuse coolant!@#$%!

Please also send the link for BMW's recommendation for hose replacement every 6 years, as mine is getting to that point too.

It might just be a N55 thing. See bottom of page under "recommended".

https://www.newtis.info/tisv2/a/en/f...lines/IEIjMkuc

[bavarianride]

Originally Posted by F32Fleet

It might just be a N55 thing. See bottom of page under "recommended".

https://www.newtis.info/tisv2/a/en/f...lines/IEIjMkuc

Makes sense, so a thermostat job on a 5-year old car should also include new coolant hoses.

It is interesting that N20/N26 does not have this recommendation, so it can be a heat capacity thing(the I6 hoses work harder than I4's).

Hmm it is a good idea to peruse newtis daily then.

[Billfitz]

Originally Posted by F32Fleet

It might just be a N55 thing.

That kind of recommendation is usually the result of experience. It would be interesting to see if that footnote appeared prior to 2015.

[bavarianride]

Originally Posted by Billfitz

That kind of recommendation is usually the result of experience. It would be interesting to see if that footnote appeared prior to 2015.

Does your post imply that this may be added post LCI?

[Billfitz]

It implies that the N55 went into service in 2009, so it would likely be 2015 before repair manuals recommended hose changes at 5 year intervals based on experience. It's a very unusual recommendation, for the most part cars don't have any replacement schedule for hoses, you just replace them if they fail, unless the reported failure rate within that relatively short interval is unusually high.

[F32Fleet]

Originally Posted by Billfitz

It implies that the N55 went into service in 2009, so it would likely be 2015 before repair manuals recommended hose changes at 5 year intervals based on experience. It's a very unusual recommendation, for the most part cars don't have any replacement schedule for hoses, you just replace them if they fail, unless the reported failure rate within that relatively short interval is unusually high.

It might be something as simple as cost of labor. Think of it like this, the thermostat and WP might get changed once or twice (every 6-9 yrs) during the lifetime of the car so change the hoses when you're down there simply because it's a PITA to get to.

Edit: Also they're not in a location where you can easily inspect (squeeze) them to determine if they need to be changed out.