HT/HS

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Is there that much significanse to HT/HS if one oil has a 3.2 HT/HS and another oil has a 3.5? It seems the ideal HT/HS for a performance car would be 3.5 or greater. So if your a M1 user, 0w-40 would be preferable. Interesting how the Mustang Cobra R uses a 0w-40, but Corvettes use a 5w-30 M1, which only has a HT/HS of 3.2. There must be more to it then just these numbers.....
 

tai

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Austin, TX
quote:
Originally posted by buster: It seems the ideal HT/HS for a performance car would be 3.5 or greater.
Where or how did you arrive at this? Just curious.
 
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Greencastle Pa.
SAE paper #980702 looks at the relationship between wear and HT/HS viscosity,the lower this number is should produce less drag and higher fuel economy but under stress would shear through,then the FM/AW additives would come into play to reduce friction and wear.
 

buster

Thread starter
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quote:
but under stress would shear through,then the FM/AW additives would come into play to reduce friction and wear.
Dr T. I was wrong, it is 15w-50 I believe. Interesting about the HT/HS. The reason I figured High performace cars would want a highe Ht/hs is because of the stress the engine puts on the oil. this is why many high hp cars use heavier weight oils. Ls1 engines must be easy on the oil to run M1 5w-30, or like RB said, other additives come into play which answers my question about there is more to it then just this particular number being so crucial. Thanks!
 

Patman

Staff member
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Ah yes, I remember the 2000 version. I don't believe it got the 15w50 M1 in it though, although I could be wrong. Considering it's based on the Ford 4.6 modular engine, it's doubtful Ford would recommend a thicker oil for that over it's 4.6 cousins. But anything's possible these days, I thought I heard someone mention the 390hp supercharged 2003 Cobra comes with 5w20 in it! [Eek!]
 
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Dixie
One thing to keep in mind is that if oil analysis shows the oil has sheared signfiicantly, then the HT/HS viscosity has been reduced as well. The wide range (0w-40, 5w-50) formulations are more prone to shearing, due to the # of polymeric thickener blended in. If oil pressure is marginal (less than 15 psi/1000 rpms of engine speed), then going to a heavier oil will normally reduce main/rod bearing wear. TooSlick
 
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6,388
Location
Washington St.
quote:
Originally posted by RB Shannon: SAE paper #980702 looks at the relationship between wear and HT/HS viscosity,the lower this number is should produce less drag and higher fuel economy but under stress would shear through,then the FM/AW additives would come into play to reduce friction and wear.
There are a few oils with both high HT/HS numbers and "Energy Conserving" rating. Mobil 1 0W-40, Schaeffer #701 5W-30 & #703 10w-30, some Amsoil oils, and probably others. Ken
 

Patman

Staff member
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Oakville, Ontario
quote:
Originally posted by Dr. T: From Mobil's website, it says that the Cobra R uses 15-50 as factory fill.
The Cobra R was only made one year though, in 1995, and it used a 351 Windsor engine. Old technology. The newest Mustangs with the 4.6 do not specifiy this thick oil, not even the 390hp supercharged Cobra.
 
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