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re: "The VIs are long chain polymers that, when cold, are in more-or-less in
straight lines but 'curl up' when hot to increase the viscosity of the oil. "
I might have that bass-ackwards. Didn't have time to look it up this morning.
Bob
----- Original Message -----
From: "Bob Spidell" <bspidell@comcast.net>
To: "healeys" <healeys@autox.team.net>
Sent: Wednesday, June 10, 2015 7:47:33 AM
Subject: Re: [Healeys] oil weight
I'd stick with 10W-50 if you don't need the cold weather capability. The bigger
the 'viscosity gap'--e.g. 5W-50 is 45, 10W-50 is 40, etc.--the more VIs
(viscosity improvers) are added to a base oil. The VIs are long chain polymers
that, when cold, are in more-or-less in straight lines but 'curl up' when hot
to increase the viscosity of the oil. The bigger the 'gap' the lower the
viscosity of the base oil--10W-50 might have a base viscosity of 7, for
instance (just an example, I don't know the exact number)--and 5W-50 might be
3, etc. The VIs get 'sheared' in use and the hot viscosity goes down as a
result. At one time, at least, 10W-40 was recommended against by some car
manufacturers (BMW, I think), though my father has used it for many years with
no problems.
I now use Valvoline VR-1 10W-50. Used Chevron 10W-50 for many years when it was
available at Costco.
Bob
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<html><body><div style=3D"font-family: Arial; font-size: 12pt; color: #0000=
00"><div aria-label=3D"Compose body">re: "The VIs are long chain polymers t=
hat, when cold, are in more-or-less in straight lines but 'curl up' when ho=
t to increase the viscosity of the oil. "<br></div><div aria-label=3D"Compo=
se body"><br></div><div aria-label=3D"Compose body">I might have that bass-=
ackwards. Didn't have time to look it up this morning.<br></div><div =
aria-label=3D"Compose body"><br></div><div aria-label=3D"Compose body">Bob<=
br></div><div><br></div><hr id=3D"zwchr"><div style=3D"color:#000;font-weig=
ht:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Aria=
l,sans-serif;font-size:12pt;" data-mce-style=3D"color: #000; font-weight: n=
ormal; font-style: normal; text-decoration: none; font-family: Helvetica,Ar=
ial,sans-serif; font-size: 12pt;"><b>From: </b>"Bob Spidell" <bspidell@c=
omcast.net><br><b>To: </b>"healeys" <healeys@autox.team.net><br><b=
>Sent: </b>Wednesday, June 10, 2015 7:47:33 AM<br><b>Subject: </b>Re: [Heal=
eys] oil weight<br><div><br></div>I'd stick with 10W-50 if you don't need t=
he cold weather capability. The bigger the 'viscosity gap'--e.g. 5W-5=
0 is 45, 10W-50 is 40, etc.--the more VIs (viscosity improvers) are added t=
o a base oil. The VIs are long chain polymers that, when cold, are in=
more-or-less in straight lines but 'curl up' when hot to increase the visc=
osity of the oil. The bigger the 'gap' the lower the viscosity =
of the base oil--10W-50 might have a base viscosity of 7, for instance (jus=
t an example, I don't know the exact number)--and 5W-50 might be 3, etc.&nb=
sp; The VIs get 'sheared' in use and the hot viscosity goes down as a resul=
t. At one time, at least, 10W-40 was recommended against by some car =
manufacturers (BMW, I think), though my father has used it for many years w=
ith no problems.<br> <br> I now use Valvoline VR-1 10W-50. Used Chevr=
on 10W-50 for many years when it was available at Costco.<br> <br> Bob<br> =
<br class=3D"moz-cite-prefix"></div></div></body></html>
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