[DeTomaso] Oil temperature and wear

Tomas Gunnarsson guson at home.se
Fri Feb 6 17:42:29 EST 2009


Dave,

I use 5W-50 and 5W-40 engine oil in all my cars and it pours similar to the ZF gear lube I use. I don't have the exact viscosity for that oil but it's a figure close to 75W90. Since I do most of my oil pouring at room temperature I guess a 5W-xx oil and a 10W-xx oil are pretty similar cold.

Tomas
  ----- Original Message ----- 
  From: Dave Londry 
  To: Tomas Gunnarsson 
  Cc: DeTomaso Forum 
  Sent: Friday, February 06, 2009 11:29 PM
  Subject: Re: [DeTomaso] Oil temperature and wear


  Hey I see that in Wikipedia Tomas,
  ................................................
  "API viscosity ratings for gear oils are not directly comparable with those for motor oil, and they are thinner than the figures suggest. For example, many modern gearboxes use a 75W90 gear oil, which is actually of equivalent viscosity to a 10W40 motor oil."
  ..................................................
  and I can understand that the hot end of the curve is similar, but they don't pour alike when cold?
  dave

  Tomas Gunnarsson wrote: 
Gear oil isn't that much different from engine oil in viscosity. They use a different grading to avoid mixup.

Tomas

----- Original Message ----- 
From: "Dave Londry" <davel at emspace.com>
To: <kenn_green at yahoo.com>
Cc: <detomaso at realbig.com>
Sent: Friday, February 06, 2009 9:02 PM
Subject: Re: [DeTomaso] Oil temperature and wear


  I don't think 250F is magic Ken.
It's keeping the viscosity at the operating temperature over some magic 
number,
which is a property of a ton of engine clearances and local pressures.
His chart says maybe that's 10 to 15 cSt for that flavour of 911.

15-50 keeps you above that line a lot longer, but it's harder to pump.
Straight 50 was terrible when cold and gear oil would  break something 
in the pump drive.
dave

Ken Green wrote:
    I found this article on oil temp:
 
http://www.elephantracing.com/techtopic/oiltemperature.htm
 
It looks like they think above 250 really accelerates wear.  It that a common view?
 
Ken
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