Motul 300 Working Well in Transaxle

I just changed the transaxle fluid on my 996 with 77k on it and am really happy with the result. I ended up buying 3 liters of Motul 300 after researching all the options and taking some advice from others on here. It shifts noticeably better now. More �buttery� for the lack of a better word and gears change more effortlessly. Gearbox seems to wake up a little faster on cool, fall Michigan mornings as well. My car has an LSD as well, and I don�t hear anything unusual and it handles as it always has. So just another +1 for Motul 300. Not sure how it�ll work long term, but short term this was a worthwhile effort.

Nice ! I have the same 3 liters sitting in my garage and will be changing the fluid as well as the fill and drain plugs this weekend before track day in 2 weeks. Thanks for posting up your experience.

I just pumped Delvac into mine. Haven�t driven it yet though.

Does your car need a seperate lsd additive?

Factory LSD needs an oil with a friction modifier. I think Delvac has it. I know that PTX has it.

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So based on my research... no. The LSD does not call for any additives. The rationale behind that is beyond my engineering know how, but according to the owners manual and other reputable resources, it does not. I think it could be something to do with the way the LSD works (mechanical vs. friction-based) but the factory fill for both LSD and non-LSD is the same. Either a Mobile or Shell product, which are both expensive and difficult to find. After doing a ton of research, the Motul 300 was one of the only oils that surpassed the factory fill on the low (cold) end and the hot end of specs. So I went with it. Again, I've only had it in there for a few days, but so far so good. It's fun to do a relatively low cost, quick fluid change on your car and get an immediate positive benefit. It really does shift noticeably better!

I too was going to consider Delvac due to all the Porsche racing use and other recommendations and I'm sure it's a great choice. Being in Michigan though and this being my daily driver, I passed on Delvac and went with Motul because Delvac was reported to be very stiff when cold. Michigan winters can be brutal and I wanted it to shift as crisply as possible on even the coldest days.

just ordered the motul from amazon, next job on my list

I also used Motul 300 on my last oil change and noticed a difference as well. Most noticeably notchiness and difficulty getting into first in colder temps were really improved.

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How is it compared to Porsche tranny oil?

Im sure my 2nd synchro is probably toast. But the Delvac made no difference in the cold 2nd gear shifting. After it is hot, it shifts ok most of the time. I now have M300 in there. But have yet to drive it.

no real noticeable difference after the motul. I didn't have any real issues prior so this was more peace of mind. No idea when it was changed prior. one more job off the list!

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I've heard that the OEM may be better in that case, just the right concoction of friction modifiers for the 996 tranny. Anyone?

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not sure how long the previous oil was in there but the car had 135k km when I changed it. Its possible it could have been original oil so I probably would have noticed a difference with delvac/oem.

Drove it today. Got really excited because I got a successful shift into 2nd without a grind. But then when I got home at dead stop it was grinding again. Seems sporadic. But I guess I�d say that the m300 did improve it a bit.

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Exceeds factory oil cold and hot, is that opinion or objective? That's good, just trying to confirm.

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Like all of us, we want to be sure we are using the right product for a particular application. I absolutely love Motul products and run their engine oil and brake fluid. But my research is counter to yours. Read the following copy and paste from a Pelican DIY article on replacing the diff carrier. You also need to make sure that you fill your transmission with fluid that is compatible with your differential. Typically a manufacturer will have some recommendations for transmission gear oil that works well with their particular differential. If you use oil that is too slippery, you may reduce your torque bias and render the LSD less effective. If you use oil that is not slippery enough, you may increase the bias and encourage premature wear of the clutch discs inside of the LSD. YMMV

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Thanks Hal, I actually read that the other day as well. As someone else who is still contemplating what fluid to replace their gear oil with, one major question remains for me. Why does Porsche spec the same fluid for 996 manual transmissions with or without the LSD? My 04 C2 has no LSD unfortunately, so I wouldn't mind a gear oil with some more slippery qualities. I dont have any grinding or persistence in notch shifting. However, not sure if it just me or my clutch, but I find it nearly impossible to get a quick 1st to 2nd shift. I do have the numeric shifter installed, but it was the same prior to installation.

Bumping this up as I'll be doing a transmission oil change soon as well. Seems like the fluid options people have used are: factory Porsche fluid, MobiLube PTX, Mobil Delvac and Motul 300. Has there been a consensus on the best option? It seems like some applications could benefit from different fluids, such as with or without LSD. What about the front diff for C4S cars? I'm curious about what's best for: Standard manual transmission with factory LSD (and without) if it makes a difference Can the same oil be used for the front diff in AWD cars? Are there preferred options for those of us living in colder climates?

As the original poster, as mentioned, I went with Motul 300 Gear oil. I have a Carrera 2 with factory LSD. The "proper" fluid for this car is the MobilLube PTX, but I went with the Motul option because it's what I had on hand and fit the spec. My main concern was would this be OK with my LSD, but my logic said if Porsche recommends the same fluid (Mobile PTX) for both cars with and without LSD, then why would I have to spec a different fluid for mine? Which is why I went with the Motul 300 Gear. On paper it was nearly the same or better than the mobile product and even for a premium fluid, much cheaper than the PTX. Being a nerd for this type of stuff, I still consulted a Porsche transaxle repair specialist since I'm sure he's seen the worst of it. His response was while he said they use the MobileLube PTX, he said the Motul 300 product I selected was fine. As far as the LSD goes, he said the pre-tension on the factory LSD for a 996 is very weak, and they lose their effectiveness fairly quickly. Sometimes in the first year or two of ownership if driven hard. He said that mine being a 1999 with 70,000 miles was almost certainly not operating at this point. I'm not sure how true that is, but the guy rebuilds nothing but Porsche Transaxles for a living, so I'm inclined to believe him. I just wanted to make sure I wasn't doing any damage which my choice. I'm fairly confident I'm not. If it turns out I am, I'm sure it's not too late to add a little friction modifier if needed. As of now though, I'm just going to run it as is. As far as a long term report goes: I'm in chilly Michigan and have a few thousand miles on the new fluid now: So far I'm still seeing it's shifting much more smoothly. It seems to go into gear with a bit more ease and while it's still a little stiff on a cold morning, it's much better than it was. Overall, a significantly better feel to the gearbox with the Motul in there. Side note: after changing it at 70K, the fluid was BLACK. There weren't any flakes or anything in the fluid, just the normal shimmering when inspected with a light, but it's something I'll be changing more often than prescribed. Especially as I continue to rack up the miles. Hope that helps!

Matt, thanks for following up and the long term update. Much appreciate it. I've had my clutch slave done, replaced the broken clutch power spring and now a clutch & flywheel (ouch $) as I'm at 80k miles I wanted to complete the service with a fresh fluid to know everything is sorted for a while. I'm curious that if the MobiLube PTX is the recommended fluid, why is it so hard to find. I've only seen 2 on line retailers sell it.

I think because it's not a high-volume consumer product here in the States, mostly to be sold in bulk to dealerships and repair places. I have seen it at Pelican, Suncoast and ECS online. It's just so expensive for what it is. The Motul was available at my local foreign autoparts store and even O'Rileys had a few liters in stock.

I've used regular Automatic Transmission Fluid (ATF) after I replaced the pinion bearing but only for a couple 100 kms to flush out any leftover bearing material. I know, the ATF is not meant for a differential gearset but I used it anyways for a few days as cleaning agent. The shifting was very smooth, a lot smoother than when I switched to Motul 300.

Makes sense. In some of my vintage cars, I've run atf in a gearbox in the winter as the shifting was much smoother. Then back to a heavier gear oil in the warmer months. For this application I wanted something to leave in there longer term and year round.. The ATF probably works great as a flush though. There's just a delicate balance of compromises going on though with these Porsche transaxles. Need to have the right amount of bite for the synchros to work, the right kind of friction for the LSD to operate and all of this needs to do triple duty as differential fluid as well. At the end of the day, we're probably overthinking it. The manual just calls for "SAE 75 90W" and I'm sure anything in that weight will be just fine.