04-16-2010, 12:36 PM
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Member
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Join Date: Mar 2010
Location: Denver, CO
Posts: 622
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Quote:
Originally Posted by JCL
Quote:
Originally Posted by sunny5280
Arguments pro "change the ATF":
- BMW recommends it at 100K mile intervals. Which coincidentally, is when your warranty is over. They don't want you changing it during the warranty period. Once that is over, any failure is at your risk. Of course, they would never be that calculating. Irrelevant. They're recommending the fluid be changed. You're not implying they're recommending a service which offers no benefit or runs an excessive risk of damaing the vehicle are you?
- No fluid is lifetime. Lifetime being defined as never change. This is a position, not an argument. It is a fact thus making it an argument.
- Fluids act as a detergent and become dirty with use. Actually, the ATF includes detergent additives. When those additives are all gone, it would be a reasonable time to change the fluid. The fluid gets dirty, but that is why there is a filter. Therefore changing the fluid restores those lost qualities the fluid offers. Fluid changes should also include a filter change (as well as cleaning of the magnet) you are removing particulates which could become lodged and cause damge. This one benefit alone may have prevented my VB failure and saved me a lot of money.
- The protective qualities of lubricants breaks down over time. Well, oil never stops being slippery, the lubrication qualities never fade away. The fluid does need to be incompressible (to work the actuators), and to be a heat conductor. There are additives to prevent foaming, and friction modifiers for the clutches. So, if the additives are depleted, the fluid could benefit from being changed. However, those very high mileage transmission being reported (on original fluid) suggest that the additives do in fact last a very long time. Perhaps even the component's lifetime. Perhaps? Suggest? Not confidence inspiring.
- Every other fluid in the vehicle is subject to change at regular intervals.How about your AC refrigerant (which lubricates the compressor), or the grease in the CV joints. They are lifetime too. I suggested shock absorbers before, but that got shot down. How about universal joints? Tie rod ends? Ball joints? Steering shafts? All things that used to be lubricated before we went to lifetime lubrication. There are not many places to use a grease gun on a modern vehicle any more. Yes these items wear and eventually require replacement.
- Other vehicle manufacturers recommend ATF changes. That would be a good reason to follow their recommendations, to keep your warranty valid. But aren't we talking about BMWs here? Are BMW transmissions somehow more resilient to the factors which affect other manufacturer transmissions? I think we all know the answer is no.
- Arguments con "change the ATF":
- In 2002 Mike Miller, head technical editor of BMWCCA, made the recommendation to avoid ATF changes due to his observed increase in subsequent transmission failures.
- Numerous web sites making the same recommendation as Mr. Miller.
- Numerous mechanics and BMW technicians making the same recommendation. I can add this same claim to the "pro change ATF" list. My mechanic hasn't seen a correlation despite doing many, many ATF changes (maybe it's because he does them properly where others claiming the opposite are not). Nor did the three BMW dealers I contacted a couple of days ago.
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Comments included above in red. |
My responses in blue.
Quote:
Originally Posted by JCL
I should clarify that I don't necessarily think that ATF should never be changed, or that it should always be changed. I do think that readers should make their minds up after understanding the risks and rewards.
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It seems we've been agreement the entire time.
Quote:
Originally Posted by JCL
There is no conclusive data either way.
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Yet the con "change ATF" people act as if there is. My position is, and always has been, there's no data to show a correlation between changing the ATF fluid and subsequent transmission failures. Therefore it's an urban legend, folklore, wives tale, what-have-you.
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