How often should gearbox and axle oils be changed

With all the discussion about engine oil changes, it has prompted me to wonder about transmission oils - do the additives wear out or do these just keep going? Should they be changed?
Regards Tony
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automatic) and differential oil every 30,000 miles. I like synthetic oils like Redline oil or Royal Purple and neither require any additives.
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for BMW with engine M54
read "Engine Reliability"
http://www.bmwworld.com/engines/m54.htm
: With all the discussion about engine oil changes, it has prompted me to : wonder about transmission oils - do the additives wear out or do these : just keep going? Should they be changed? : Regards Tony :
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"Jim" wrote

The question is, what is their definition of "lifetime"? If the tranny fails and has to be replaced at 100K miles, then surely the oil inside has lasted it its entire lifetime, but oh what a short life it was.
Pete
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A BMW transmission and differential should last ALOT more than 100K miles. Interestingly, before it went to lifetime fluids, the recommended change interval was 30K miles for transmission, both automatic and manual, and differential. Then again if you lease your car or get a new one every 2-3 years, then "lifetime" is fine as you care less about a car that has more than 100K miles on it. Sad....
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Sad?
Your view is lost on me. If one is not comfortable with "lifetime", then get the fluid changed. Most modern cars have 100k fluid in the trans and diff(s), but there is no reason the fluid can not be changed on your own schedule -- presumably a shorter interval.
If one leases, then they generally do so to avoid these kinds of maintenance issues since there is no lease on the planet that will rack up sufficient miles to need a fluid change of any kind -- other than the motor oil and _perhaps_ coolant and brake fluid.
Even if the trans and diff fluids have a limited lifespan, a lease car will never approach the life of these fluids without incurring siginficant over-miles charges on the lease -- a fee that will pretty much destroy any advantage that leasing might offer the average driver.
The definition of "lifetime" is the normal and customary life of a vehicle, not the maximum possible life. Industry standard says that most cars last about 8 years, and get about 15k miles per year. 8 X 15 = 120, so it seems reasonable to me that lifetime means about 100000 miles or so. I see nothing at all "sad" in a lfe expectancy like that. To be sure, I keep my cars much longer than that, and I put more miles on in a year -- or, I used to but my annual miles have been cut in the past 18 months or so, but that's me.
I think that if the dealership (factory) covers the warranty to 100k on the original fluid, then it must be okay to keep it in that long. If the warranty expires and the original fluid is still in the car, then I think a smart person would go ahead and change it and pray the components last another 100k miles. Odds favor a failure that is not related to fluid changes ...
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Are the extended service intervals genuinely a function of lubrication improvements, or is the marketing department getting the final say? The auto trans has a different and improved fluid which was originally called "lifetime fill" and is now on a 100K schedule. The manual trans is now filled with synthetic ATF vice a dedicated transmission lube (primarily to resolve customer complaints about sluggish cold shifting) and is "lifetime fill." But did the lube get that much better (used to be 30K) or is it just to make 50K "free" maintenance an affordable marketing ploy?

All true.

Who's definitition? Certainly the 3-4 year lease holder. Possibly the average 1st owner. OTOH, lots of cars get second owners and lots have "lifetimes" at least twice what you propose.

BMW's warrantee is 50K. Fine for infant mortality of components, but unlikely to catch the neglected or marginally serviced ones. I'd like to see a 100K warrantee, particularly on drivetrain and cooling system (radiators being a weakness in recent BMW's), but I doubt BMW is going to offer one.
I intend to have my E39 for some time (perhaps beyond 200K), so the fluids are going to be changed on the pre-free maintenance schedule. There are consumable components (pads and rotors, wiper blades, etc) that I expect to replace, but I'm hoping that the only unscheduled replacements will be a radiator and water pump ... hopefully not after a catastrophic failure.
R / John
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"John Carrier" wrote

That's interesting. Got a link to more info? Last I've heard the OEM fluid was still some type of GL4/GL5 75w-90 synthetic manual gear oil...
Thanks, Pete
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Not off the top of my head, but you can google it. Most of those who want to replace the OEM fluid use Redline D4 ATF or Royal Purple Synchromax (http://www.royalpurple.com/techa/tranxref.html ). I went with Redline MTL which is a bit more viscous, a bit better lube, but requires a bit of deliberate shifting when cold (below 40F or so).
Diff takes a 75/90 synthetic gear oil, and the P/S (forgot about it, didn't you) D4 ATF.
Engine oil. The service is somewhere in the 12-17K mile range based on the indicator. E-39's and E-46's just monitored fuel quantity consumed (a pretty good approximation of service actually). The earlier cars were a bit more exotic (cold starts, etc) and the later cars evidently are too. The biggest problem with extended service is the additive package tends to go the earliest. You get good lubrication, good filtration, but some accumulation of (catch-all word) sludge. Particularly noticable in V-8's. With newer cars (not M's!), typically 5W30. I think any good synthetic will do (BMW, Mobil 1, etc). If you're particular: Amsoil, Redline or R/P. I'd go with the boutique stuff if I planned on using the service interval recommendations.
I think any decent synthetic lube changed at somewhat aggressive intervals will maximize the service life of the component. Go with the boutique stuff if you want to stretch things a bit.
Coolant. Every 2 years from production date with BMW coolant or its equivalent (which nobody seems to know exactly).
Brake fluid. At least every 2 years with proper spec.
If you're on a lease or won't own the car for 200K+, it's not worth it. This is the EXTENDED maintenance plan (which is remarkably similar to the pre-free-maintenance plan).
R / John

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John Carrier wrote:

I've used both Redline and RP and like both. For cold shifting, Redline recommended D4 ATF in my manual transmission.

blue is Valvoline Zerex G48, which happens to be EXACTLY the same thing as BMW coolant:
http://tinyurl.com/wdth9

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John Carrier wrote:

That's all nice to do and all. But when I asked my dealer about changing the "lifetime" fluid in my E46 323, the quote was like $1200.
I don't know what's in that fluid to make it so expensive...
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It's just chock full of profit
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The auto fluid is very expensive and they've conveniently determined the change interval to be 100K (well outside 50k "free" maintenance). $1200 still sounds outrageous. Do you have an independent BMW mechanic in town? Even given the high fluid cost (several $100), it ain't THAT hard to do a service.
I also suspect that there's an alternative to the OEM fluid (it's just a ZF trans, right?) that's cheaper than what the dealer sells. (Don't know ... the benefits of a manual trans.) I don't think there's a magical elexir that, unless used, will trash the trans ... but that's just my opinion. If it's out of warranty, it's just the "well, if I don't mess with it, it'll be fine, or if I only use the OEM fluid at $XXXX it'll be fine or if I change it for just a really good synthetic fluid I might screw up" factor. That's the hell of it. Nobody knows. Even Mike Miller (BMWCA and Bimmer mag tech guy) doesn't have an answer.
Perhaps you could buy the OEM fluid (I'm sure there's a given amount required for a flush/fill) and DIY. I did all my fluids for relatively little cost using Redline MTL, 75w90 gear oil and D4 ATF (P/S). Used BMW coolant for the flush.
OTOH, you could inquire major boutique fluid makers (Redline, Royal Purple, Amsoil) and find out if they have a fluid for your trans. There's GOT to be a solution cheaper than $1200.
R / John

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John Carrier wrote:

I tried the "leading" indie German-car mechanics in my town, and they refused to do it. Said they'd never seen a E46 with a failed tranny.

Blah.
Well, they labor seems to be several hours, for an experience mechanic with a lift. Could be a darn evil job for the DIY'er...

You'd think, wouldn't you?
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The highly overpriced fluid is probably ESSO LT71141. Many people complain but do no research. In fact, AMSOIL ATF meets the ESSO LT71141 spec as well as BMW 7045E, and ZF TE-ML 14A, B, & C.
I am not an AMSOIL dealer, but I do use their ATF in place of the BMW "lifetime" fluid.
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