Drivetrain Questions and info regarding transmissions, clutches, etc.

Diff oil: 75w-90 or 75w-140?

Old Jan 5, 2010 | 09:52 PM
  #46  
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There are also many M3 owners running a 75w140. The difference is not really noticeable. Maybe a thinner oil would net you a couple horsepower too huh?
 
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Old Jan 5, 2010 | 09:54 PM
  #47  
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how would differential/gear oil gain you hp?
 
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Old Jan 5, 2010 | 10:00 PM
  #48  
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Just going by the logic above in a sarcastic way. If thicker gear oil would make you slower than surely a thinner gear oil would make you faster.
 
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Old Jan 5, 2010 | 10:06 PM
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^^^ but being faster doesnt always mean "gaining hp"

it could possibly help reduce parasitic loss (negligible though I think)... but hp is derived from engine... I understand what you are saying though (now)
 
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Old Jan 5, 2010 | 10:09 PM
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Actually if you were measuring hp/torque on a dyno, he would be correct. It takes xx hp to overcome the friction in the engine/tranny/drivetrain. Any reduction of friction would show up as a hp increase on the dyno. Since the majority of hp/torque measurements here are done on a dyno, this is what I assumed he meant. He should clarify though
 
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Old Jan 5, 2010 | 10:09 PM
  #51  
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Yeah, it was what I meant. It's been a long day
 
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Old Jan 5, 2010 | 10:17 PM
  #52  
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I liked the ninja edit
 
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Old Jan 5, 2010 | 10:19 PM
  #53  
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Originally Posted by Jeff92se
Actually if you were measuring hp/torque on a dyno, he would be correct. It takes xx hp to overcome the friction in the engine/tranny/drivetrain. Any reduction of friction would show up as a hp increase on the dyno. Since the majority of hp/torque measurements here are done on a dyno, this is what I assumed he meant. He should clarify though
its not adding hp though, its lessening hp loss at the wheels - you know as well as I do you can only add hp at the engine.

and in any case gear oil isnt likely to make a notable difference in most situations
 
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Old Jan 5, 2010 | 10:21 PM
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^^ That was my original point and why I started to say it was a bad analogy. It is hardly noticeable at least to me.
 
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Old Jan 5, 2010 | 10:22 PM
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^^^ its understood now... but somehow Jeff and I will find a way to act like we dont understand each other
 
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Old Jan 5, 2010 | 10:28 PM
  #56  
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LOL... I have noticed that in several threads.

The main reason I went with the 75w140 was for the added protection. I do track my car from time to time and have also done some drifting on a wet skid pad. Given the additional abuse I put it through I wanted some more protection.
 
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Old Jan 5, 2010 | 10:30 PM
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a finned cover and/or cooler would be good insurance.
 
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Old Jan 5, 2010 | 10:32 PM
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Yes. I have considered these
 
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Old Jan 5, 2010 | 11:25 PM
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Originally Posted by OCG35
its not adding hp though, its lessening hp loss at the wheels - you know as well as I do you can only add hp at the engine.

and in any case gear oil isnt likely to make a notable difference in most situations

I dunno Mike. Is gaining a few hp via using a slicker engine oil count as "at the engine"? If no, then cool.

Then yes, then I don't see how using a slicker gear/diff oil can't do the same.

But of course I knew what you meant. I was being technical like you Mike.
 
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Old Jan 6, 2010 | 12:08 AM
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Originally Posted by TwilightBlue
Yes. I have considered these

zack (RareJDM) has a very nice kit... dunno if/when they will come out with it (as product for sale), but if you are seriously considering it you might want to hit him up ~
 
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