Tiptronic Rear Differential Oil Change - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Hey Guys, Just recently hit the 90k mark and I'm about to change the transmission fluid and the rear differential oil in my 98' tip (btw, thanks for the great write-up Andy!). Anyhow, after searching through posts for a couple of hours and my bentley book, I'm amazed at the lack of information pertaining to changing the rear differential oil. I haven't been able to find any info other than the type of oil and quantity. It appears the tip's have a fill plug on the side but no drain plug. And of course, unlike the manuals, the trans. and rear diff. don't share oil on the tips. From what I've read in the Bentley, I need to remove the differential cover and the drive axle and flange to let the oil run out!! Which sounds like a pretty ridiculous job to me ...So considering there is just under a liter of oil in there, I'm thinking of going in through the fill plug with a turkey baster with a bit of hose to siphon out the oil and then refill with new Royal Purple. Does anyone have any helpful info they'd care to share? I think i'm going to hit up pelican for the ZF LT71141 ATF and the other trans. odds and ends. Anyone by chance have a source or any info for the rear diff. fill plug replacement seal? Any other better sources for ANY of the above mentioned items? Thanks in advance for your insight and help guys!! -ian

Perfect timing. Wondering the exact same thing as I get ready to do this job. Surely there is a better way to drain and fill the diff. without yanking the axle out!

Wow! I'm surprised at the silence. Has no one else done this fluid change? Is there no insight to be shared? Throw me a bone here fellas, haha -ian

My mechanic was joking the other day that the only way to completely change the rear diff oil on the Tip box was to turn the car on its side.... He said that after checking my oil and it was really dirty AND I had paid another indie to change that oil just a month ago... talk about being fleeced... Sorry, I know that doesn't help.

look up one of your big boat buddies,use their 12 volt oil changing pumps,just snake the tube into the fill hole till it hits the bottom

Are you 100% confident that it's the EXACT same oil as the Esso/Mobil LT 71141? Reason I ask is the ZF part number is NOT 71141 from what I understand.

The TIP takes Pensotin ATF-1 and the final drive takes a 70-90 weight gear oil. I just did my service for the TIP. It took 6 liters, some use up to 7 liters. Next is the final drive oil change...I like the electric pump idea.

Sorry guys, but the Tip equipped cars require that you pull an axel and side cover to drain the diff, that is the way Stuttgart designed it................

Any reason why the electric fluid pump as used in boats wouldn't work? Taking a look online seems like it would work perfectly. Snake the hose in, turn the pump on, suck out fluid then use a regular gear oil hand pump to pump a litre worth of new stuff in... Any oil recommendations for the tiptronic diff? I know it's supposed to be 75W90 but can't find any info on the correct GL rating as in GL4 or GL5 or brand recommendations...Pelican sells "Titan" diff oil but I would rather use a Redline or Swepco product if available as I'm sure many of you reading this would too.

Hey Guys, A couple details: I bought the ZF ATF fluid that pelican sells. If you search their site for Esso/Mobil LT 71141 for AT Boxsters, two products show up; Pensotin ATF-1 and ZF ATF. The ZF cost just a little more. I went with it simply because the trans. was built by ZF. There wasn't any product number listed on the site that I saw. However, the fluid showed up today and here's what the containers have to say: ZF-LifeguardFluid5 ATF 21010N28 Semi-synthetic high performance oil for use in 5-speed automatic transmissions, for cars only. I, as well, haven't found any specs. regarding the GL rating for the rear diff. oil. My bentley book simply specs. "Hypoid gear oil SAE 75W90". I'm thinking of using Royal Purple product. The local auto part store has small electric pumps for rent for removing the oil. I'm going that route and not pulling the drive axle. Alright, I'm diving into this change first thing in the a.m. I'll definitely post when I'm done! -ian

Chances are that a hose and pump will not get all the old oil and sediment out, so you may have to refill and dump several times to get everything. By that time, you could have pulled the axel and cover............ As for the best/correct gear oil, experience over the years had taught me that Porsche is prone to use very unusual and even unique gear box and diff oils, several major oil companies have openly admitted they do not have anything comparable because of the strange specs Porsche uses. As far as small blenders like Redline, Royal Purple, or Amsoil; while they have consistently claimed they have a matching product for just about everything, only problem is that most of the time they are misleading you with thinly veiled marketing hype; which is why we do not use any of their products..............

JFP in PA, Thanks for the info on what not to use... Now, drawing from your experience over the years; care to share what the best/correct gear oil IS?

Hey Guys, A follow-up: I finished the fluid change this morning. Everything went pretty smoothly. I followed the excellent write-up that Andy put together on this forum along with the Pelican write-up. I let my trans. sit and drain overnight without the cover or filter on. I drained 4 1/2 liters total and then managed to put in 5 1/2. After starting up the car and taking it up to 40 C, I then drained a further 2 1/2 liters of partially contaminated fluid (in an effort to flush), then refilled 2 1/2 liters of new fluid back in. So all in all, I ran 7 liters of new fluid through the system but basically put 5 1/2 liters in. I then sealed everything up and went for a drive! The car is shifting through gears absolutely, noticeably smoother. It's awesome. Now, on to the differential... What looks like it shouldn't be too much hassle, has just been ridiculous! I haven't been able to get the fill plug to break loose. The Bentley book says the plug torques at 22 ft lbs. I've easily put over a hundred on it trying to get it off, without any luck. It looks like it's got locktight or something similar on it and It's such a small space to work in! Anyhow, I'm going to go to an indie shop monday morning and see if those guys can get it open. I'm just amazed, lol. But, happliy, the creepy, guess-work part of the project is done! :dance:

We get ours from Porsche..............

From the factory, there is often a sealant like material on the plug that really makes difficult to remove the first time. Once it is loose, you will be fine. We clean the factory sealant off the treads and put a drop of anti seize on it before re-torque......

Awesome. Thanks for the info. That plug is making me crazy, lol.

Just went through that this weekend. Best way to get the plug out is to pull off the diagonal body brace underneath, it's just a bolt and a couple of nuts. After that you can with the right combination of extensions and breaker bar get a nice 90 degree angle on your ratchet/breaker bar and get the plug out with NO PROBLEMS. I spent 20 minutes trying with the brace in place and couldn't do it. Pulling the brace took all of 2 minutes and after that it was as easy as a girl from Surrey...

Can someone point me to Andy's Tiptronic Rear Differential Oil Change write-up?

There are also other ways to change the ATF. For example the Tom Eckard method: Englisch Regards Markus

Quotes source post: 410275

How much differential fluid I should add back in? I was only able to get about .3 liter of fluid out of rear differential on my 2003 boxster. Any info would be appreciated.