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Discussion Starter #1
This transmission oil doesn't seem to have much traction in the Lotus community, but I know it's getting quite popular elsewhere. My Elise has a Torsen and so I think it would benefit from having a GL-5 rated oil. The popular choice, Redline MT-90, is only GL-4 rated while the Motul Gear 300 is GL-4/5 rated. Does anyone have any experience using the Gear 300?
 

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I think the GL-5 on Gear 300 LS scares people away, because traditionally to reach the required pressure standard GL-5 gear oil has phosphorous/sulfur additives which eat away at yellow metal synchros (brass/bronze).

I think (but am not positive) that Gear 300 has a more modern borate additive which doesn't eat yellow metals, since the listings I've found say it's safe for synchronized gearboxes. No guarantees on that, though.

There's a lot of "go with what works for other people" here, hence the obsession with 5W40 TDT even though other oils are probably just as good, which is probably why people just talk about MT-90.
 

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Discussion Starter #3
I think the GL-5 on Gear 300 LS scares people away, because traditionally to reach the required pressure standard GL-5 gear oil has phosphorous/sulfur additives which eat away at yellow metal synchros (brass/bronze).

I think (but am not positive) that Gear 300 has a more modern borate additive which doesn't eat yellow metals, since the listings I've found say it's safe for synchronized gearboxes. No guarantees on that, though.

There's a lot of "go with what works for other people" here, hence the obsession with 5W40 TDT even though other oils are probably just as good, which is probably why people just talk about MT-90.
I do get a bit of the "go with what works" feeling here. However, I'd be using Gear 300 and not Gear 300 LS. As I understand it, Torsens don't require LSD friction modifiers, but they still spec a GL-5 fluid. The Gear 300 will give me a GL-5 rated fluid without the LSD friction modifiers.
 

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I swapped the stock fluid on my 08 Exige and it has limited slip diff.. Bought the 300 LS off sector...shifting has improved cold and hot...
 

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Which is better for the factory trans with factory LSD? Gear 300 or Gear 300LS? Or just go with MT-90?
 

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To answer my own question, stock trans and factory Torsen LSD need Motul Gear 300. Not "LS"
 

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GL-4 and Gl-5 Gear Oils

Use the grade that manufacturer recommends. GL-5 is NOT GL-4. GL-5 is NOT better than GL-4. They are just different grades. I would be very concerned about putting any GL-5 gear oil into a transmission with synchronizers. These are made of bronze. There are plenty of stories about synchros being destroyed by 'fancy' fluids.

Redline has GL-4 (MT-90) and GL-5 (74W90 NS) fluid. Why do they recommend MT-90? Because, this is the manufacturer's spec.!

Motul 300 is GL-4 and GL-5 certified, so it would appear to have a less corrosive additive package....

Anti-slip additive for plate-type LSD's with synchros is another problem. With Torsen LSD, none is required or should be used.

With brass synchros fluid choices are difficult.

I run a dog box with Torsen, so GL-5 all the way!!! (After, I confirmed that no bronze bushings were used by the manufacturer and GL-5 was the recommended fluid.)

Anton


I do get a bit of the "go with what works" feeling here. However, I'd be using Gear 300 and not Gear 300 LS. As I understand it, Torsens don't require LSD friction modifiers, but they still spec a GL-5 fluid. The Gear 300 will give me a GL-5 rated fluid without the LSD friction modifiers.
 

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I was close to using MT-90 until the post "I've seen what happens when you use MT-90 etc" and it scared me off. I'm lost now lol.
 
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