Question about 6 speed transmission fluid change...
 

I'm not certain of the service history of my 2000 Boxster S, so I'd like to change out all fluids starting with the transmission fluid.

I've used the search function, but can't find info I need.

Would Mobil Delvac 75w90 Synthetic Gear oil be an acceptable choice, or should I use factory fill gear oil from the nearest (1.5 hours away) stealership?

Any thoughts & commentary appreciated.

Use the factory fill, we have not found a viable substitute...............

Second that, have tried just about all the possible brands and found the factory fluid works best

I used Swepco 201 to no ill effects. Pelican and other places recommend and sell it. Don't look for the forum seal of approval however. Lots of folks here will poo poo it because they like buying really expensive German liquids and will tell you that anything else will cause certain catastrophe.

Some of us use it because (1) It is not all that expensive; (2) It always works flawlessly; (3) We have never had a paying customer come back with any type of complaints about it; and (4) UoA's run on it says it has a very long life, usually well beyond the OEM recommended change cycles. It is a good product….

Not saying that Porsche fluids are not good just saying that there are other options.

Sometimes it is good to have an alternative such as with the fluid in my ZF Range Rover slushbox. The factory said the unit was sealed for life, sticker on the bottom of the pan even says so. This has not turned out to be the case and you must change the fluid and filter at 100k miles to avoid problems. The factory fluid is not available due to M&A activity. Mobil one synthetic ATF is a suitable alternative for this application.

Also not everyone is close to a dealership. Sometimes you cannot wait to get the right stuff and you need some right now stuff instead.

If you buy other than Porsche fluid, be sure to get GL4 rated oil. I used Red Line. The Red Line is good stuff. The only dislike is the slightly stiff shift when cold. After warm up no issues. JFP in PA is correct. The porsche fluid is much better. My next change will be with Porsche fluid.

As Rocket stated, I have no issues at all with shifting, EXCEPT for the initial gear change when the transmission is cold. I can confidently say it's not driver error, as I am 46 and have been driving standard shift since 14 years old.

I would occasionally get ever the slightest crunch on the initial 1 - 2 shift after backing the car out of the garage after it has been sitting for a few days. If I short-shift on that initial 1 - 2 shift, nothing.

At 47,000-ish miles last July my Indie did the LN IMS bearing update. He also swapped out the throwout bearing and replaced the RMS (while we're in there), and found a flywheel still within spec, a pressure plate in good condition and a surprise: a recent clutch disc the previous owner never informed me about.

I guess I'll have to take a drive into Toronto or to London to the nearest dealership for transmission fluid. A three hour road trip. Aw shucks.

Hi Steve,

On another note, where did you get your IMS upgrade done? What about pricing?

These guys may carry your Porsche gear lube in Waterloo

New and Used Porsche Parts Canada, New Porsche Parts Canada, Used Porsche Parts Canada, Whale Tail Canada

Personally, I would (and did) go for convenience, and head on down to the local auto parts store where they have a great selection of excellent hypoid oils. I like Valvoline Synthetic combined GL-4/GL-5 rated. Don't get just a GL-5, get the combined rating.

As I understand GL-5 is the best for ring & pinion gear loads, but GL-4 is best for synchonizers. With a transaxle like we have, you would like to have a combined rating.

Also, if you have a torsen type limited slip, you probably don't want the Royal Purple or Red Line super exotic type oil that has some kind of friction reducing semi-solid beads in it. As I understand, that can reduce the effectivness of the limited slip.

brian325is,

I had Mike and Dave at German Autotech in Waterloo do my IMS surgery. Great guys. I had it back in under a week, even though they had to order in all the parts.

The dual row bearing, installed, with new t/o bearing & RMS was just over $1800. The removed bearing, by the way, was close to total failure. In my case, I'm glad I spent the $$ to have it replaced.

I never thought to call Whaletail on trans oil, they are located less than 5 minutes from me!

I put this in in January then read all the you won't be able to shift in the cold warnings. It was recommended by a person who track a car 6 to 7 times a year, and is connect to a dealership . It worked the same as the old oil. I felt no change. The 03 most likely had the Mobil PTX in it from new

There is no one in Canada that will ship it? We ge ours from Sunset Porsche in Beaverton, OR; so I know it can be shipped..............

I just love gear oils with this supposed type (both GL-4 and GL-5) of API ratings; if you read up on what the specs actually mean, you would discover that what makes a given product a “GL-5” rated lube, prevents it from every holding a “GL-4” rating (the difference is an additive package specifically for improving the performance of certain types of limited slip differentials, but which is also known to attack certain metal alloys, like the synchronizer rings used in transmissions which require GL-4 rated lubes).

Straight GL4 is how I interpreted the requirement. Lots of GL5 and GL4/GL5 around, but hard to find the straight GL4 synthetic around here. It took a little research time for me to find the straight GL4. Turned out to be at an Indy parts shop about 2 miles from my house. $11 per liter.

Probably the best (particularly in low temps) full synthetic GL-4 around is Castrol Syntorq LT, but due to marketing agreements through OEM's, it can be harder to find. We use it exclusively in Nissan 6 speeds requiring GL-4 lubes due to the alloys used in the double synchronizers on the first and second gears, works very well and holds up for a long time.

Mobilube from the Porsche dealer
 

I'm finally getting around to doing a transmission fluid change on my 2001 Boxster S.

I've been looking through all these different forums about what the best "gear oil" is for my 6 speed manual transmission.

I gave up.

I went to the dealer and was ready to pay the $30 per liter that I've seen mentioned, but they sold me "Mobilube HD Plus 80W-90 Gear Oil" for $8 a liter. I was surprised. I asked about synthetic, and/or Porsche branded oil, but they assured me that this was what Porsche recommends for this model.

-for what it's worth...

https://mobiloil.com/en/gear-lubricants/mobilube-hd-plus

We've had a few epic technical discussions of this issue of gearbox oil.
A few of us who are fairly well educated in tribology beat it to death .We searched both in USA and Europe for an alternative. We failed. Use Search for the geekish details. If when you drain the old oil it is filthy maybe there is a case for using an inadequate alternative as a flushing oil and then replace with the correct(Shell) oil.
If you are curious about how complicated the chemistry of these oils is- visit BITOG .
After a few hours there you will wonder why people who select oil because the "like it" make a post in a thread like this.This isn't a Facebook fan page!
JFP's recommendation is what we geeks reluctantly came to accept the very best advice. This has been acknowledged many,many times. So unless you can publish a comparison of the chemistry of a new alternative oil to the Porsche-approved ,Shell product ,nothing has changed. Substitutes may work well enough(?) but that is a pragmatic question, not a technical one.

Simple. Go with the real stuff. I tried an 'economical' alternative gear oil for my first change and it didn't work nearly as well. Went back the Porsche OEM stuff (made with unicorn tears based on the price here in Canada) and it was like night and day. Avoid disappointment, go with the real thing. You won't regret it.