Gear Oil Recomendation for New Zealand

[daltvater]

At the risk of being told to do a search....

I don't think I can read another thread about gear oil. So much conflicting information.

I've got a 915 with LSD. 100% track use. I'm located in NZ and as such only have access to Motul and Brad Penn.

Use Brad Penn for the engine. Thinking I'll use Brad Penn for the gearbox?

https://penngrade1.com/products/gear-lubricants/

Thinking 80w90 without the LSD additive? Does that sound right to you guys?

[psychoideas]

I'm in Aus and I always use SWEPCO 201> I get it here vis Amazon.
Cheers.

[Jeff Alton]

If you can get the Brad Penn gear oil, use it.

Swepco is good too, but the hype it got in years gone by makes me laugh. It is very good gear oil for your application though.

[Ian Comerford]

I use Motul 75/90 Transynd in my non-LSD 915 and find it better than 201. I would think their LSD version would be fine for you.

[daltvater]

Originally Posted by Jeff Alton

If you can get the Brad Penn gear oil, use it.

Swepco is good too, but the hype it got in years gone by makes me laugh. It is very good gear oil for your application though.

Sweet thanks Jeff. I needed a nod of approval. The BP stuff is 80w90 GL-5 and covers a LSD. seems perfect.
https://penngrade1.com/products/gear-lubricants/penngrade-1-limited-slip-gl-5-gear-oil-sae-80w-90/

I cannot get over how fun a 915 is to drive at the track. I've got 3300 track kms on the box since I've owned it. Mated to a 3.6 with 270 wheel hp. I hope I can get another 3,000+ track kms out of it. Keeps you honest for sure but that is why its so good.

[daltvater]

Originally Posted by psychoideas

I'm in Aus and I always use SWEPCO 201> I get it here vis Amazon.
Cheers.

Thanks, like most things going to NZ, Amazon is charging $200 for the shipping.

[Matt Monson]

The Penngrade Classic oil is only GL4 rated. They don’t offer a mineral based Gl5 that I know if.

I’ve been putting my overseas customers in Motul HD 80w90 for a while now.

[daltvater]

Originally Posted by Matt Monson

The Penngrade Classic oil is only GL4 rated. They don’t offer a mineral based Gl5 that I know if.

I’ve been putting my overseas customers in Motul HD 80w90 for a while now.

Thank you Matt! I would not have figured this out without your suggestion here. Motul has so many choices and isn't very helpful when asked about which to use.

Just to confirm this looks like the stuff....
https://motul.co.nz/product/hd-80w90/

Also you were right about PennGrade. Their very helpful response here...
(hope they don't mind me posting this)

Dan,
Thank you for contacting D-A / Penn Grade / Penn Grade1 Lubricants and for your inquiry. Great to hear from our friends in New Zealand!

Let me start by indicating that the best source for any / all engine lubricant recommendation for your 915 LSD gear box is the OEM (Original Equipment Manufacturer). Best place to start is actual owner's manual....then perhaps a reputable service department / dealership. Please note that without the benefit of actual OEM information, my only source for lubricant recommendation(s) is various forms of in-house reference material (see below) and experience. If possible, please verify all of the aforementioned before taking action.

With that said......regarding OEM recommendation, my in-house reference suggests the following:

Porsche

1950-89

Manual Transaxle
911 (1986-77) – All: 90 GL-5
924, 944 80W, 80W-90 GL-5
928 75W-90 GL-5


Differential
924, 944 (1989-77) 90 GL-5
928 (1983-78) 90 GL-5

Now....I have researched competitor products that are often mentioned in Porsche threads. The one product often listed is the Swepco 201 Multi-Purpose Gear Lube......which I understand to be a GL-4 80W-90 non-synthetic gear oil. GL-4 and GL-5 are very different animals.......and yes, the Swepco product does contain limited slip. Our PennGrade 1® Limited Slip GL-5 Gear Oil SAE 80W-90 would NOT be a suitable replacement as it contains GL-5 level chemistry....not GL-4. The problem with using a GL-5 gear lubricant in systems calling for a GL-4 level of performance are the potentially damaging effects of the higher concentration of extreme pressure agents like sulfur and phosphorous found in GL-5 gear lubricants on yellow metal (brass, bronze, copper). GL-4 level is essentially ½ the treat rate of GL-5 level. So.....a GL-5 gear lubricant would NOT recommended for use in GL-4 applications......conversely, GL-4 would NOT be recommended in systems requiring GL-5 (not enough EP).


We have a terrific, conventional based GL-4 gear oil (PennGrade1 ‘Classic’ GL-4 80W-90), but it does NOT contain limited slip that your 915 LSD gear box likely requires.

Please feel free to contact me should you need further assistance. In the interim, please confirm actual lubricant recommendation for 915 LSD gear box before acting

[Jonny042]

If you've been reading oil threads till your eyes bleed you probably saw this one:

http://forums.pelicanparts.com/porsche-911-technical-forum/1098741-915-dog-box-conversion-kit.html

It turned into an oil thread. Short version is I switched from Swepco 201 to Motul Motylgear 75W90 and love it. It's not just subjective, either - shifting speeds as per my datalogging improve by 300-400 millisecond, from as much as second flat to 650-700 milliseconds.

The difference when driving is significant.

Originally Posted by daltvater

At the risk of being told to do a search....

I don't think I can read another thread about gear oil. So much conflicting information.

I've got a 915 with LSD. 100% track use. I'm located in NZ and as such only have access to Motul and Brad Penn.

Use Brad Penn for the engine. Thinking I'll use Brad Penn for the gearbox?

https://penngrade1.com/products/gear-lubricants/

Thinking 80w90 without the LSD additive? Does that sound right to you guys?

[winders]

The Motul Motylgear 75W90 specs specifically states for use in transmissions "without limited slip".

[Jonny042]

Originally Posted by winders

The Motul Motylgear 75W90 specs specifically states for use in transmissions "without limited slip".

Good point. Could add LSD modifier if it turns out to chatter?

[daltvater]

Originally Posted by winders

The Motul Motylgear 75W90 specs specifically states for use in transmissions "without limited slip".

In reading previous threads on gear oil there seems to be a thought that the LSD additive is too slippery for 915 syncros? I have no clue.

[daltvater]

At the track this week I had what Motul suggested I use in it...

Motul Gear 300 SAE 75w90 100% synthese.

Shifts had to be slow and I had to double clutch. It was not good.

[winders]

Originally Posted by Jonny042

Good point. Could add LSD modifier if it turns out to chatter?

I don't know why Motul says "without limited slip".

As best as I can tell, the additives for the LSD might make it chatter less but also actually make the LSD less effective.

For a 915 and its balk ring synchro design, I worry about any gear oil that has a synthetic base.

[winders]

Even the Motul HD 80w90 spec sheet says for use "without limited slip". Maybe it is fine for LSDs but it will chatter in street use.

[Marknado4000]

Hi daltvater, im in Auckland as well and managed to get Kendall 'special limited slip' 80w90 from Performance Parts in Takanini. It was a couple of years ago. Its been amazing in my 915, could be worth seeing if they still carry it! (if the kendall works for you)

[Jonny042]

Originally Posted by daltvater

At the track this week I had what Motul suggested I use in it...

Motul Gear 300 SAE 75w90 100% synthese.

Shifts had to be slow and I had to double clutch. It was not good.

Like Scott says, that's a full synthetic and probably a poor choice. (Edit - was it the LS version?)

[daltvater]

Originally Posted by Marknado4000

Hi daltvater, im in Auckland as well and managed to get Kendall 'special limited slip' 80w90 from Performance Parts in Takanini. It was a couple of years ago. Its been amazing in my 915, could be worth seeing if they still carry it! (if the kendall works for you)

Thanks for the lead, I called but no go. Said there is no longer a supplier for Kendall in NZ. GOtta love our vast amount of choices in NZ

[daltvater]

Originally Posted by Jonny042

Like Scott says, that's a full synthetic and probably a poor choice. (Edit - was it the LS version?)

It doesn't say LS on it. Just Gear 300. What did I put in there?

[Jonny042]

Originally Posted by daltvater

It doesn't say LS on it. Just Gear 300. What did I put in there?

Motul has a staggering array of gear oils and they all seem to be named similarly.

I based my decision on several factors including cold viscosity and ended up on the semi-synth 75W90. I'm not the first one to try it, others who have tried it also like it.

For your track car the recommendation of the Motul HD 80W90 conventional (not the plain 80W90 which had added moly for "slipperyness" which you dont want) is probably sound, but the semi-synth 75W90 is thinner when it's cold, and thicker when it's hot. The tech docs on the motul website are pretty good.