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Oil shear ? #4472692
07/28/17 06:34 AM
07/28/17 06:34 AM
Joined: Feb 2008
Posts: 1,058
MA.
Camprunner Offline OP
Camprunner  Offline OP
Joined: Feb 2008
Posts: 1,058
MA.
If an oil inside a motor shears down a grade is it still protecting at that level or is the oil and add pack compromised to a point where the oil is not lubracating properly?

Re: Oil shear ? [Re: Camprunner] #4472697
07/28/17 06:40 AM
07/28/17 06:40 AM
Joined: Sep 2013
Posts: 10,448
Indiana
dlundblad Online happy
dlundblad  Online Happy
Joined: Sep 2013
Posts: 10,448
Indiana
It's still protecting to an extent, but how much is it being ran AFTER it sheared down?

One would need a UOA to know for sure. I personally like oils with higher starting TBN's for this reason.


03 Jeep WJ 4.0 200k Castrol Edge 10w40 HM Fram XG16
02 Volvo S60 2.4T 177k M1 0w40 Mahle OX149D
97 Chevy Blazer 4.3 149k Rotella T5 10w30 Supertech ST3980

Re: Oil shear ? [Re: Camprunner] #4472704
07/28/17 06:53 AM
07/28/17 06:53 AM
Joined: Jul 2016
Posts: 1,090
Europe
SonofJoe Offline
SonofJoe  Offline
Joined: Jul 2016
Posts: 1,090
Europe
When an oil shears, only the VII polymer shears. The other stuff in the oil (ZDDP, dispersants, detergents, AOs, FMs etc) absolutely doesn't shear. So other than for a drop in viscosity, the oil continues to do what it's supposed to do.

Re: Oil shear ? [Re: Camprunner] #4472712
07/28/17 07:01 AM
07/28/17 07:01 AM
Joined: Jan 2013
Posts: 354
West Yorkshire, UK
NGRhodes Offline
NGRhodes  Offline
Joined: Jan 2013
Posts: 354
West Yorkshire, UK
popcorn

Re: Oil shear ? [Re: Camprunner] #4472716
07/28/17 07:10 AM
07/28/17 07:10 AM
Joined: Sep 2015
Posts: 2,260
Malaysia
zeng Offline
zeng  Offline
Joined: Sep 2015
Posts: 2,260
Malaysia
A sheared oil (and by extension, a fuel-diluted oil) is still offering protection, albeit at reduced protection level as a result of reduced oil film thickness consequential upon reduced operating viscosity.
However main bearings and con-rod bearings might predominantly still stays in hydro-dynamic lubrication regimes offering complete protection from abrasion/adhesion wear mechanisms.
Having said this, in the valve train systems and cylinder liner/piston ring tribo-pairs, there is increased levels of unfavourable boundary lubrication and mixed lubrication regimes ...... which are mitigated by essentially functioning anti- wear additive package.
The same cannot be said of gear-train systems, however.

Re: Oil shear ? [Re: zeng] #4472724
07/28/17 07:22 AM
07/28/17 07:22 AM
Joined: Jan 2017
Posts: 1,139
USA
ArcticDriver Offline
ArcticDriver  Offline
Joined: Jan 2017
Posts: 1,139
USA
Originally Posted By: zeng
A sheared oil (and by extension, a fuel-diluted oil) is still offering protection, albeit at reduced protection level as a result of reduced oil film thickness consequential upon reduced operating viscosity.
However main bearings and con-rod bearings might predominantly still stays in hydro-dynamic lubrication regimes offering complete protection from abrasion/adhesion wear mechanisms.
Having said this, in the valve train systems and cylinder liner/piston ring tribo-pairs, there is increased levels of unfavourable boundary lubrication and mixed lubrication regimes ...... which are mitigated by essentially functioning anti- wear additive package.
The same cannot be said of gear-train systems, however.


So I understand better.

If I am using a 5w40 and it shears to a 30w, then isn't it still offering the same level of protection as a 30w?

If my vehicle manufacturer suggests I should use a Xw40, then aren't they factoring in that Xw40 oils are going to shear?


Multiple Diesel and Gasoline vehicles
Re: Oil shear ? [Re: Camprunner] #4472743
07/28/17 07:57 AM
07/28/17 07:57 AM
Joined: Jun 2017
Posts: 209
NY
DdDd Offline
DdDd  Offline
Joined: Jun 2017
Posts: 209
NY
An engineer with a half brain would spec a weight that is acceptable including shear for the duration. Then again a lot of hokey decisions get made by marketing too!

Oil film strength is a function of pressure and viscosity. If you can provide either in sufficient quantities you're doing good. My personal opinion is people who go up a weight to "stay in spec" are over thinking things. Modern engines have tighter tolerances and better oil pumps compared to yore.

I have yet to see an engine wiped out by 20weight oil. You'd think every 2017 model would be stranded on the side of the road.

Re: Oil shear ? [Re: DdDd] #4472749
07/28/17 08:04 AM
07/28/17 08:04 AM
Joined: Jan 2017
Posts: 1,139
USA
ArcticDriver Offline
ArcticDriver  Offline
Joined: Jan 2017
Posts: 1,139
USA
Originally Posted By: DdDd

Oil film strength is a function of pressure and viscosity. If you can provide either in sufficient quantities you're doing good. My personal opinion is people who go up a weight to "stay in spec" are over thinking things. Modern engines have tighter tolerances and better oil pumps compared to yore.



Or more like a "resistance to pressure", right?


Multiple Diesel and Gasoline vehicles
Re: Oil shear ? [Re: Camprunner] #4472762
07/28/17 08:23 AM
07/28/17 08:23 AM
Joined: Oct 2015
Posts: 2,654
Balearic Islands , Spain
FordCapriDriver Offline
FordCapriDriver  Offline
Joined: Oct 2015
Posts: 2,654
Balearic Islands , Spain
Shearing is the destruction of the viscosity index improvers in an oil, it will cause the oil to get thinner, and it can increase the solid deposits in an engine.


1975 Ford Capri II Ghia 3000 V6, - Shell Helix HX3 20W-50 w/ 20% Rimula R4X 15W-40 HDEO.

1988 Ford Escort Mk4 Xr3i Cabrio, - Shell Rimula R4X 15W-40, w/ 30% Helix 3 20W-50.
Re: Oil shear ? [Re: Camprunner] #4472769
07/28/17 08:33 AM
07/28/17 08:33 AM
Joined: Jan 2009
Posts: 13,837
Illinois
tig1 Offline
tig1  Offline
Joined: Jan 2009
Posts: 13,837
Illinois
Isn't it better for an oil to shear a tad than to oxidize?


2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters

Re: Oil shear ? [Re: FordCapriDriver] #4472774
07/28/17 08:35 AM
07/28/17 08:35 AM
Joined: Jan 2009
Posts: 13,837
Illinois
tig1 Offline
tig1  Offline
Joined: Jan 2009
Posts: 13,837
Illinois
Originally Posted By: FordCapriDriver
Shearing is the destruction of the viscosity index improvers in an oil, it will cause the oil to get thinner, and it can increase the solid deposits in an engine.


Isn't solid deposits caused more from oil thickening(oxidizing) than shearing?

Last edited by tig1; 07/28/17 08:36 AM.

2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters

Re: Oil shear ? [Re: tig1] #4472802
07/28/17 08:54 AM
07/28/17 08:54 AM
Joined: Feb 2016
Posts: 669
NJ, USA
MotoTribologist Offline
MotoTribologist  Offline
Joined: Feb 2016
Posts: 669
NJ, USA
Originally Posted By: tig1
Originally Posted By: FordCapriDriver
Shearing is the destruction of the viscosity index improvers in an oil, it will cause the oil to get thinner, and it can increase the solid deposits in an engine.


Isn't solid deposits caused more from oil thickening(oxidizing) than shearing?

I'm also a bit confused at how shearing increases deposits....I'll await the explanation before further comment.

Re: Oil shear ? [Re: DdDd] #4472914
07/28/17 10:14 AM
07/28/17 10:14 AM
Joined: Sep 2015
Posts: 3,861
Connecticut
69GTX Offline
69GTX  Offline
Joined: Sep 2015
Posts: 3,861
Connecticut
Originally Posted By: DdDd
I have yet to see an engine wiped out by 20weight oil. You'd think every 2017 model would be stranded on the side of the road.


Wiped out vs. just simply excessive wear?

Real world experience seems to back up the advice of these experts too. Some of the best data from the modular community has come from Nick McKinney:

Quote:
"I have said it a few times now, heavier oil has better protection especially in the cam bores. ---I get 2-3 sets of modular heads a week through here, and any lay person just from looking would pick the 500,000 mile cores run on 15W-40 diesel spec all their lives over the typical Mustang head run 50,000 miles on the light stuff"


Fleets typically run their vehicles 250,000 to 500,000 miles! I've heard Nicks experience echoed several times by fleet managers. They wouldn’t run a 5w-20 oil for one minute.


----------------

2001 Lincoln Cont 4.6L DOHC/ 39K mi / QS HM 5w30 / FUG XG2
1999 Camaro SS M6 /19K /Mobil 1 0w40 /Fram UG /GM MTL-ATF
1969 Ply GTX/RRs
Re: Oil shear ? [Re: MotoTribologist] #4472918
07/28/17 10:17 AM
07/28/17 10:17 AM
Joined: Oct 2015
Posts: 2,654
Balearic Islands , Spain
FordCapriDriver Offline
FordCapriDriver  Offline
Joined: Oct 2015
Posts: 2,654
Balearic Islands , Spain
Originally Posted By: MotoTribologist
Originally Posted By: tig1
Originally Posted By: FordCapriDriver
Shearing is the destruction of the viscosity index improvers in an oil, it will cause the oil to get thinner, and it can increase the solid deposits in an engine.


Isn't solid deposits caused more from oil thickening(oxidizing) than shearing?

I'm also a bit confused at how shearing increases deposits....I'll await the explanation before further comment.

Well, nowadays it isn't such a problem as modern oils contain less VIIs, and higher quality, more resistant VIIs, but back in the 70s when VII technology was still rudimentary and a lot of multigrade oils were absolutely packed full of them suchas some 10W-40 and 10W-50 mineral oils, when they were destroyed they did form sticky deposits inside engines and caused rings to stick etc etc etc..... or that is atleast what i've read!


1975 Ford Capri II Ghia 3000 V6, - Shell Helix HX3 20W-50 w/ 20% Rimula R4X 15W-40 HDEO.

1988 Ford Escort Mk4 Xr3i Cabrio, - Shell Rimula R4X 15W-40, w/ 30% Helix 3 20W-50.
Re: Oil shear ? [Re: 69GTX] #4473011
07/28/17 12:14 PM
07/28/17 12:14 PM
Joined: Jan 2009
Posts: 13,837
Illinois
tig1 Offline
tig1  Offline
Joined: Jan 2009
Posts: 13,837
Illinois
Originally Posted By: 69GTX
Originally Posted By: DdDd
I have yet to see an engine wiped out by 20weight oil. You'd think every 2017 model would be stranded on the side of the road.


Wiped out vs. just simply excessive wear?

Real world experience seems to back up the advice of these experts too. Some of the best data from the modular community has come from Nick McKinney:

Quote:
"I have said it a few times now, heavier oil has better protection especially in the cam bores. ---I get 2-3 sets of modular heads a week through here, and any lay person just from looking would pick the 500,000 mile cores run on 15W-40 diesel spec all their lives over the typical Mustang head run 50,000 miles on the light stuff"


Fleets typically run their vehicles 250,000 to 500,000 miles! I've heard Nicks experience echoed several times by fleet managers. They wouldn’t run a 5w-20 oil for one minute.


Third party hear-say doesn't count. smile

Last edited by tig1; 07/28/17 12:24 PM.

2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters

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