oil weight
05-22-2008 | 05:17 AM
#12
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Posts: 756
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From: New Hartford CT
STP and those type of oil additives are nothing more than a polymer with some base stock and maybe a very slight treat of additive.
Adding it to a straight weight oil(30) could bring the viscosity up to a 40 but the polymer that is used in STP is a inexpensive one so ove a short time the polymer will shear and you will have a straight 30 again.
(The oil can shear any less than a straight 30 because straight weights have no polymers.)
Instead of running a straight 30 w/ an additive use a straight 40,(if you want to stay with a straight weight) if not use a good multi-viscosity (20w50 comes to mind) motorcycle oil.
Ken
Adding it to a straight weight oil(30) could bring the viscosity up to a 40 but the polymer that is used in STP is a inexpensive one so ove a short time the polymer will shear and you will have a straight 30 again.
(The oil can shear any less than a straight 30 because straight weights have no polymers.)
Instead of running a straight 30 w/ an additive use a straight 40,(if you want to stay with a straight weight) if not use a good multi-viscosity (20w50 comes to mind) motorcycle oil.
Ken
05-22-2008 | 06:33 AM
#13
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Joined: Aug 2007
Posts: 337
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From: Waterford, MI
The car in that avatar is a production 1993 Mustang Cobra. They only made that model one year. I think they had about 5 - 10 more hp than a stock GT, and had a different body kit. They still seem to bring big money in good shape. There were some R versions available to race teams only I believe. They were a no air, no power option deal, and they were stripped down for weight.
05-22-2008 | 07:05 AM
#14
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From: Cape Coral
NEVER, EVER use 10w40 in ANYTHING GM powered. 
That particular multi weight oil breaks down faster than anything else. Mercury recommends straight 40w, 25w-40, or 20w50, if I'm memory serves me correctly.
Read here: http://www.mercurymarine.com/service...qs/fueloil.php
This thread contains some interesting reading too: http://www.boatengine.net/t/055289.html
I'm a big fan of synthetic oils, but that's not what we're talking about.
That particular multi weight oil breaks down faster than anything else. Mercury recommends straight 40w, 25w-40, or 20w50, if I'm memory serves me correctly.
Read here: http://www.mercurymarine.com/service...qs/fueloil.php
This thread contains some interesting reading too: http://www.boatengine.net/t/055289.html
I'm a big fan of synthetic oils, but that's not what we're talking about.
Last edited by fabricator; 05-22-2008 at 11:16 AM.
05-22-2008 | 07:28 AM
#15
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Joined: Feb 2008
Posts: 715
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From: Michigan
NEVER, EVER use 10w40 in ANYTHING GM powered.
That particular multi weight oil breaks down faster than anything else. Mercury recommends straight 40w, 25w-40, or 20w40, if I'm memory serves me correctly.
Read here: http://www.mercurymarine.com/service...qs/fueloil.php
This thread contains some interesting reading too: http://www.boatengine.net/t/055289.html
I'm a big fan of synthetic oils, but that's not what we're talking about.
That particular multi weight oil breaks down faster than anything else. Mercury recommends straight 40w, 25w-40, or 20w40, if I'm memory serves me correctly.
Read here: http://www.mercurymarine.com/service...qs/fueloil.php
This thread contains some interesting reading too: http://www.boatengine.net/t/055289.html
I'm a big fan of synthetic oils, but that's not what we're talking about.
05-22-2008 | 07:39 AM
#16
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Posts: 442
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From: Cape Coral
A 10w oil starts out as a base 10 weight oil, and a 20w oil starts out as a base 20 weight oil, put simply. The polymers that are used to create the '40' in the 10w40 oils breaks down faster that those used in the 20w40 oils. Oil chemistry is very complicated, and I won't pretend to be an expert. OilDoc does a good job of explaining oils in this thread: http://www.boatengine.net/t/055289.html
05-22-2008 | 10:39 AM
#17
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From: Wagoner OK
Thanks i think ill go with 20w40. the avatar is actually a picture of a car like mine i just sold. Jayhawk explained exactly what it is. They did come out with gt-40 heads stock. with a blower and exhaust they are a 400 horse at the rear wheel car.
Last edited by 31cigg; 05-22-2008 at 10:46 AM.
05-22-2008 | 03:58 PM
#19
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Joined: May 2004
Posts: 5,762
Likes: 1
Weights that would work for you in my opinion:
30wt (if ambient temps at or around 40*F)
40wt (RP;Kendall; Castrol; Penzoil etc)
25W-40 (Mercury Semi-syn)
15W-40 (Amsoil Marine); Rotella;DelVac
15W-50 (Mobil-1) Silver Cap
20W-50 Mobil-1 V-Twin; Amsoil; RP; Redline; Castrol; Kendall etc.)
My choice for your engine:
Mobil-1 SilverCap 15W-50
$24.00/5 qt @WallyLand
Why? A lot of boaters on this board use it and tear down looks real good.
Mobil-1 V-twin 20W-50 if you can go $9/qt or Redline 20W-50 have the highest levels of anti wear additives I have seen so far.
30wt (if ambient temps at or around 40*F)
40wt (RP;Kendall; Castrol; Penzoil etc)
25W-40 (Mercury Semi-syn)
15W-40 (Amsoil Marine); Rotella;DelVac
15W-50 (Mobil-1) Silver Cap
20W-50 Mobil-1 V-Twin; Amsoil; RP; Redline; Castrol; Kendall etc.)
My choice for your engine:
Mobil-1 SilverCap 15W-50
$24.00/5 qt @WallyLand
Why? A lot of boaters on this board use it and tear down looks real good.
Mobil-1 V-twin 20W-50 if you can go $9/qt or Redline 20W-50 have the highest levels of anti wear additives I have seen so far.
Last edited by Hydrocruiser; 05-26-2008 at 12:00 PM.
