[ds968]

I have this question on another thread , but thinking this segment may be more appropriate - does the Porsche 968 maintenance booklet indicate the intervals ( mileage and/or time ) when the transmission fluid should be changed in the tiptronics ?

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[Cloud9...68]

<img src="/forum/images/smilies/968/popcorn.gif" class="smilie" alt="" /> I don't know about the Porsche world, but the topic of automatic trans fluid change intervals is one of those that brings out the most emotional responses of anything this side of politics and religion, at least in the BMW world. Anything from "You have to change it every 30,000 miles or the gears will start flying out of the casing", to "Don't ever change it! - the material that wears off the clutches mixes with the fluid to create a magic elixer that must never be touched - you'll be lucky if your transmission lives another week if you drain this potion of the gods."



I ended up changing the fluid in two of our BMWs in the 90-100K mile range, but I haven't touched the stuff in our 2003 X5 with 120K miles on it. My hunch is that for average, general use, changing it isn't essential - I'm sure 90% of the motoring public doesn't even know their transmission contains fluid, and with the average age of a car at well over 11 years, you'd be seeing dead cars strewn all over the highway if it were critical to drain and refill auto trans fluid on any kind of a regular interval. But in a performance-oriented car like a 968, particularly one that's supercharged, it probably would make sense to change it every 60K or so, but that's just a guess.



Also, you have to keep in mind that it isn't possible to drain anywhere near all of it - unless the 968's transmission is different, you can't get the stuff out of the torque converter. So you have to drain and refill it several times before you get 90+ new stuff in there. Not sure there's a universally accepted guideline here.

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[ds968]

Yeah, I have been aware of the heated debates / different schools of thought on this topic for many years .. in fact the issue is so old many assert ( though historically not confirmed with absolute certainly ) a transmission fluid change debate is what started the feud between the Montagues and Capulets. One of the reason I was wondering if Porsche has anything in their 968 service schedule on this, but not sure they have anything at all regarding any fluids changes ( coolant, brake fluid, power steeing, ...do hey even mention oil changes for that matter ? ) intervals in the manual.



Btw, out of curiosity why would a supercharged car need transmission fluid changes any more frequently than a NA car ? Or even oil changes ? Is it because the transmission gets a lot hotter while under SC boost, and so does the engine ?

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[flash]

not so much that it gets hotter under boost, as it gets hotter due to a failure of the throttle control mechanism (right foot)



as for the schedule, shame on you for not checking the maintenance schedule in your owner's manual, but it says, on page 6,7 and 8:



check fluid every 15k

change ATF fluid and filter every 30k

change oil in differential every 60k

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[94SilverCab]

"Don't ever change it! - the material that wears off the clutches mixes with the fluid to create a magic elixer that must never be touched - you'll be lucky if your transmission lives another week if you drain this potion of the gods."



[color="#282828"]How about creating a business selling old ATF ??? ("We will drain the ATF from your new BMW and replace it with Magic Elixir")[/color]



Jay

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[flash]

sounds like a job for mythbusters

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[Cloud9...68]

Jay,



Yep, that's about right.



How hard is it to change the ATF in a 968? In a BMW 3-Series, it's kind of a pain. You have to remove the pan to get to the filter, and there's no dip stick to tell you whether the level is correct. You have to put the car on a lift, fill it until fluid starts to drip out of the fill hole, then run it until it gets warm (but not too hot), and add more fluid until it starts coming out of the fill hole again. Hot, messy, and not a lot of fun.



As far as the yarn about it being bad to change your trans fluid, a guy in my group at work once had a car on which the automatic transmission started slipping, so he took it to a shop, where the mechanic asked him, "Let me guess, you just had the ATF changed, right?" Sure enough, he had. The mechanic replied that he's seen transmissions fail countless times right after a drain & fill. Strange...



But if it's relatively easy to do, and not too expensive (BMW recommends a "special" fluid that's quite pricey), it can't hurt to follow the manual's recommendation and do it every 30K.

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[flash]

the failures are due to the hydraulics and their seals. when you remove the contaminants you remove some of what was keeping things sealed up. any weak spots then show up.



something to note is that these kinds of failures usually only occur on transmissions that have not been regularly serviced. if you keep the fluid clean, you won't likely have the failures.

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[ds968]

[quote name='flash' timestamp='1406648960' post='160620']

as for the schedule, shame on you for not checking the maintenance schedule in your owner's manual,

[/quote]



No such thing came with either of my cars, unfortunately.

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[ds968]

The last time I had the transmission oil changed in my manual 968, was 17 years and 60 k miles ago  ( I believe the manual has both the trans and the differential together, so  same  fluid running through both,  as opposed to the tiptronic where they’re separated )..  It was changed back then because I had the pinion bearing fixed.  

So I was thinking the oil may be overdue for another refresh,  but surprisingly enough I’m getting flack even from places that would make money from doing this  job ; the common response is  “ Why ? sure , we can do that for you but  it’s unnecessary, there is really no breakdown point for manual transmission / differential gear synthetic oils,  they should last for the lifetime of the car “.   From experience, I do know for a fact that most oils and fluids will last easily 2 X , or even 3 X or even longer than the manufacturers’ suggested longevity , but “ lifetime“ ?!   That’s seems highly questionable ...    Anyway, I’ll probably do it just in case , because I don’t really see a downside , but what weight should I buy ?    75w-90 , or 75W-140   ?  Or maybe another weight ? 

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[ds968]

Bump - so no one here replaced their manual transmission fluid yet , or knows what the oil weight should be ?   

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[94SilverCab]

Sorry, mine was replaced when the O.S. Giken LSD was installed, but no idea what they stuck in there...

 

Sorry,

 

Jay

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[MCL968]

Let me check, I still have a can of it in the garage. BRB...

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[MCL968]

After a long winded discussion and consultation with the AMSOIL rep, my astrologer, and my stunt double, this is what was selected.

 

And, a suggestion, if I may. Remove the filler plug FIRST, and then the drain plug. Pick up a couple of spare crush washers, and be prepared to heat the area around the drain and fill plugs with a heat gun to get them to break loose.

 

I pulled the drain plug first THEN I couldn't get the fill plug out, which meant my car was effectively immobile.

 

I eventually got enough heat on the case and applied enough torque to the plug to get it to break loose, but for a while it was looking like it was going to be a tow bill to the shop. All's well that ends well I suppose.

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[ds968]

Great, and also thanks for the note on the order of removal ; those are the kind of things that tend to save a lot of headaches .  

 

p.s. I’m a big fan of Amsoil . 

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[Kim]

I always used Mobil 75W-90 synthetic.  Because of how much I drove I (i.e. dealer) replaced it several times.  They always said that Porsche recommended Mobil lubricants.

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[Waylander]

75w-90 GL5 compliant it says in the workshop manual, any oil that complies should be fine


And as above, always undo the fill plug first, and expect it to be dam tight

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[ds968]

Porsche will recommend whichever brand they’re in cahoots with at any given time, so I pay little attention to that but since I’m always skeptical about any manufacturers recommendations , I do my own research on independent studies and tests results .   Mobil1 is definitely in the top 5 brands ( consistently so ) but so is Amsoil, Redline, Motul, Royal Purple , etc .. so any of the top rated brands will do perfectly fine. 

 

The manual also recommends changing the oil every 60 K miles, so that means you should probably start considering it around 100 K miles, and since I’m past that , it’s on my to do list the next time I take the car in for any service , 

 

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