Transmission Fluid - really that hard?
 

I've read just about every post on this forum and others about recommendations for Transmission Fluid. Here are the two take aways for my 2000 Boxster S:

1) Correct oil for this is a GL-4 75W90.
2) Using a GL-5 in this transmission is BAD and will wear the yellow bits.
3) But, everyone uses a GL-5 (Swepco, Redline, Mobile1, etc) because that seems to be all that is available.

This feels very incongruent. What, pray tell, am I missing?

I just went through the same thing, I am getting ready to change the oil in my 2000 Boxster S transaxle.

I was all fired up to buy the Porsche fluid until I saw the price compared to other 75W90 gear oils...

I have a couple of gallons of Mobile Delvac 75W90 because I just did the diffs and t-case on my Toyota FJ Cruiser and I had bought extra to do the diffs on my old Tacomas. I wondered if the Delvac would be good for the Boxster, searched and read some threads (some folks have had good results with it), and then just ended up buying 3 liters of the Porsche Transmission Oil.

Out of the places I checked, I found the best price at ECSTuning for right at $30 a liter:

2000 Porsche Boxster Roadster S H6 3.2L Drivetrain Manual Transmission ES#1513799 75W-90 Gear Oil Manual Transmission Fluid - 1 Liter - 99991754600

Suncoast was a little higher at around $39.

I had to buy a few other odds and ends from them too and shipping was only around $9 so it wasn't so bad.

I would have been tempted to try some of the others, but I already have all the issues that I have seen described when using non-oem gear oil (hard shifting when cold, etc) and I didn't want to make it any worse. (I'm not sure what's in there now, I am at 108,000 and I have service records going back 50k miles and I don't see a transaxle oil change so I figure it is time). Too many folks that I respect say to stick with the Porsche oil for this one so I decided to play it safe.

I will report back once I get it changed; I am taking some time off around Christmas so hopefully I will get to it soon.

Steve

Edit: on my son's 95 Miata we used Redline MT-90 because it was almost impossible to find a true GL4 75W90 and we (he) loves it. I thought that was expensive at ~$15 a quart... until I saw the Porsche gear oil... Some places had it at over $50 a liter :)

I think with redline gl-5 you use the 75w90 'ns' formulation, where ns is non-slip or somesuch - no friction modifiers so that the syncros work ok.

Everything. Porsche uses a unique gear oil (it has no Gl rating) that is manufactured for them by an obscure branch of Royal Dutch Shell. When we questioned several manufacture's about their products for this application, the larger and apparently more honest ones (Mobil, Castrol, etc.) stated that it is an unusual product with unique specs, and that they had nothing comparable to offer because of the small market. The smaller "blenders" all claimed to have the perfect match for it; only problem was that their "matches" caused noise, hard shifting and other problems, which promptly went away when their products were drained out and replaced with Porsche's OEM fluid, which is also a full synthetic.

It's your car and you money, we only use the OEM product.

In my opinion we are lucky to have JFP and other folks like him on the forum. For me it is about trust and faith. (And Porsche doesn't always get it right, but they mostly do or else we would not love the cars the way we do) I replaced my IMS with the LN because I wanted to not worry about it. $90 for Porsche fluid vs $45 for 3 quarts of aftermarket isn't that big of a difference in the grand scheme of things. The peace of mind for doing it right is worth more to me than the extra $45-$50. And if I try one of the others and don't like it then I am out the $45 + the $90 for the oem fluid and two afternoons of grunting under the car pumping my little pump, leaking oil all over the place, etc... After changing 2 diffs and a t-case on the fj, with two more diffs and one manual transmission on the tacomas, I am worn out from the pumping. (ok that sounds bad..) I would hate to have to do it twice :)

Steve

Spoke to Pelican and Pedro about this - funny, Pedro and the owner of Pelican Parts both use the Swepco 201 in their boxsters.

But, as Steve and JFP say, for ~$50, is it really worth it? I'm sure I'd be fine with a different product, but I think I'll stick with the stock replacement as well...

I just found this bulletin:

http://bethnrayndogs.com/car_docs/Porsche/porsche/Porsche_Tech/Porsche_TECHNICAL_BOOKS/Tech_Bulletins/Gp3_4a-99-1eps.pdf

The Shell 999 917 546 00 seems to be the Porsche Oil, at least the part number matches.

The others are all in 20 liter sizes :)

Doing a search for Shell 99991754600 leads me to a lot of threads, but no places to buy.

For the amount of time I have spent researching this I have probably used up any savings from doing the job myself :)

Steve

Ok found another thread that seems to say that Audi uses the same transmission oil, for $20 a liter:

Audi Parts - Audi Parts | Audi Wholesale Parts | Audi Accessories | Cheap | Discount Audi Parts

Thread:
Rennlist Discussion Forums - View Single Post - Right gear oil for GT3?

Anybody want to try this out and report back :)

Steve

Lots and lots of race teams, and the guys over at Gbox use the Delvac 75W90, which is what I have in my 996 box at the moment (which also has a Guard LSD in it) and I'm plenty happy with it. I've run the Delvac stuff for years in multiple Porsche boxes. If you go this route, you have to buy in the gallon, NOT the quart (like you find at the local Autozone), as apparently they are grossly different fluids.

Supposedly, the "new" Audi manual trans fluid (what comes in, say, a new S5) is the cat's meow, but it's something like $60/quart from your dealer!!!

Interesting, as we just put a Gbox overhauled six speed back into a 996TT, and the paperwork that came with it said to use the OEM fluid only..............

That is interesting.. as the last time I needed fluid, I drove out to Gbox and they just pumped me 4 quarts of Delvac out of their drum.....

Perhaps it had something to do with the type of LSD you had installed, but their recommendation for every rebuild they have done for us is the OEM fluid only.

Perhaps. I am running a Guard LSD in mine (though the next time around I'm going to do the OS Giken, as Guard hasn't exactly gone in the right direction since the sale of the company).

Following up to this thread, I replaced my MT Oil in my 2000S last week with the Porsche Fluid. I have immediately noticed the following things (albeit after only 2 test drives of about 40 miles)

1. Before - whenever I would park, I would always go ahead and put it in reverse for next time, otherwise I would have a devil of a time getting it into reverse when it was cold.

2. Before, when I would first start up for the day and drive off, I would have a devil of a time going from 2nd to 3rd until it had sufficiently warmed up.

Both of these are resolved with the new Porsche MT Oil, and overall shifting is much smoother. I am not sure what was in there before or how long it was in there, but I am loving the new fluid very much, definitely worth it to me.

Steve

When I drained my transmission, I replaced with Amsoil 75w-90. No noticeable difference, or if so slim to none. Did not improve or worsen shifting conditions or noise.

GL-4: Red Line Synthetic Oil - Gear Oil for Manual Transmissions - MT-90 75W90 GL-4 Gear Oil

Just bought a 2001 Boxster S with 118,000 miles. When cold it is very slow to go into any gear. About 3 miles later it is ok. I did a drain and fill with Porsche fluid - no change. I do not know if it was ever changed before.

In my BMWs, I always used Redline in the trans and diff. BMW specs a lighter gear lube than Porsche, but I was hoping that a lighter fluid would make it easier to shift when cold. Anyone successfully using Redline and which viscosity? Thanks.

So I think that I can add some help to this thread. The oil debate seems to NEVER end, and that is due in part I think to the fact that most shops have a oil of choice. So here is the reality with regard to the 986 gearbox.

The reason that companies like Gbox and others put a disclaimer to use only Porsche OEM fluids, is for their protection. Some synthetic oils do not work well inside these gearboxes as they are simply too slick to allow the synchronizers to work at their optimum ability. As such, I myself do not recommend them. I know however that there are any number of shops that use them all the time.

The Porsche oil is quite expensive and not easy to find. There are several other oils out there that will do the job just fine, but will have their own unique characteristics. One of them will be that shifting will be stiffer when the gearbox is cold. This is NOT a bad thing. You want oil to adequately coat the synchronizers, and gears to protect them when they first start running together.

Going to a lighter fluid to remedy this cold start up feel, is not a good idea. In making the shifting slightly easier you are also wearing the internals, especially the synchronizers, more quickly. This will also result in a earlier rebuild time.

So on and on the debate goes on. Here is what most every rebuilder, at the end of the day is going to say, unless they have some oil they use on everything. Pretty much any 90 weight non synthetic oil will be just fine for your gearbox. You can spend the money on the OEM oil, which experience has shown one to work better than the other in terms of what they recommend. (get the shell oil if you can find it) Or you can certainly use a wide variety of others. Just keep in mind that synthetics CAN wear some parts prematurely, even if they are also protecting others.

As I mentioned, many shops have a favorite oil, usually one that has shown itself to work in a wide array of gearboxes. For me, I tend to recommend the Swepco 201 for the street and the 210 for the track. There are other blends that I think some people have had issues with, but these two, as far as I know have never caused any issues in any Porsche gearbox.

I hope that this is somewhat helpful. Feel free to give me a call with any more specific questions. I am always around to help.

Erik Johnson
(970) 344-7761 phone

http://986forum.com/forums/437747-post24.html
http://986forum.com/forums/437794-post26.html
http://986forum.com/forums/437800-post28.html

Erik, compelling argument about the cold starts. I will stick with the heavier fluid. Thank you!