Oil viscosity and if you can feel the difference?

[Fordiesel69]

One thing that has really been bothering me is if you can really "feel" the differnce in a slight viscosty change. Or if it is simply mind over matter. The fact is, the Ford modular 4.6L was introduced in a Lincoln in 91' and used 5w-30 up until late 2000 when they made the switch to 5w-20. This was done with no engine design changes to accompany this new spec'ed oil. Now people think this engine can only run 5w-20.

Now given this engine is spec'ed for 5w-30, with an average cSt @100 C of 10.8, why would some say the engine feels sluggish when GC 0w-30 is used with a cSt @100 C of 12.3? Are you saying with that slight change in viscosity creates a detectable drag on the engine that you would feel during throttle response? I'm confused.

 

[Bryanccfshr]

Yes, you can detect differences in engine response from differences in viscosity. You need to take into account the entire viscosity curve through the warm-up range as well. GC will be much thicker throughout the warm-up phase (assuming it's warmer than -30°) thus the engine will be more sluggish in the warm-up phase as well as a little more sluggish when completely warmed up. Seeing how most trips are 20 minutes or less a 5w20 or 5w30 energy conserving oil is going to be less viscous in all phases and therefore a driver may notice a difference in engine response.
During steady highway driving engine response is not as noticeable because this is a steady state driving phase but the additional viscosity will cumulatively require more energy to be used to shear and pump it and that energy comes from fuel.

Compare the 40°c temperatures of the oils as well and you will see what I am talking about. A 5w20 will be thinner than a 5w30 and during this phase it is likely that drivers will be going through stop lights and side streets where acceleration is needed and differences in viscosity can be felt by the driver from the engines response to his /her inputs.

 

[cmhj]

Without question you can "IF" one pays attention..............

 

[Saab9000]

I would say its wishful thinking. Its an old racers trick to run very thin oil in a vehicle to get a very slight increase in HP because of lower pumping losses, but remember racers will run 10W oil in a car or motorcycle spec'ed for 40-50W oil. Very hard to believe anyone can "feel" a 10 point difference in viscosity.

It would be an interseting idea for "Myth Busters" to do a blind test to determine if anyone can "feel" the difference in viscosity.

 

[oilyriser]

I feel the difference between 5w30 and 5w20 even when its fully warmed up, but only at small throttle openings. 15w40 big difference. 10w30 can't tell from 5w30.

 

[Blue99]

I think what drivers are really reporting is more of a difference in engine sounds or noise levels when comparing GC to other oils.

If the crankcase oil at 12.1 cSt generates a "sluggish" feel, then what happens to the performance, during the normal 5-10 minutes warm-up period, when the oil is thinning out, & may be 10 times as thick at 120 cSt or 4 times as thick at 48 cSt?

I think most of us are driving around without an accurate oil temp gage and when we consider the vehicle fully warmed up, the oil in the crankcase may still not be at the final 100C temperature and is somewhere between 12-20 cSt in viscosity.

Here's a viscosity chart to illustrate the actual viscosity levels during the engine warm-up.


Code:

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Viscosity in cSt

TEMP GC Havoline

C F 0W-30 5W-30

0 32 517 573

10 50 280 293

20 68 163 165

30 86 102 100

40 104 67 64

50 122 46 44

60 140 34 31

70 158 25 23

80 176 19 17

90 194 15.0 13.5

100 212 12.1 10.8

.

VI Index 179 159

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[Gary Allan]

Quote:

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I would say its wishful thinking. Its an old racers trick to run very thin oil in a vehicle to get a very slight increase in HP because of lower pumping losses, but remember racers will run 10W oil in a car or motorcycle spec'ed for 40-50W oil. Very hard to believe anyone can "feel" a 10 point difference in viscosity.

It would be an interseting idea for "Myth Busters" to do a blind test to determine if anyone can "feel" the difference in viscosity.

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Racers don't race with ambient temp oil.

Mobil 5w-40 vs 10w-30 synths

100C visc oil (40) 14.2 vs (30) 10.0

40C ................102 vs 62

Just the difference in 40c visc is 4X the operating visc of the lower visc oil.

4CST= fractional hp
40CST= 10X fractional hp

Expand for lower temps

The average person will not perceive minor visc variations. The average person doesn't have a lightbulb go off when something is "unright" with their car. It lingers until they get time ..or annoyed enough ..or it fails in service.

So ..I'd say the term "perceive" needs to consider the audience.

 

[TR3-2001SE]

I would think maybe at the extremes but otherwise no. I have gone from 30 to 40 and can notice no difference in milage or response. However if I went from 0w-20 to 20w-50 I could probably notice a slight difference in response and milage. Still would not be much difference but could be measured I would think.

 

[Ugly3]

Ask Gary Allen, he does it all the time in his Mini Van.

 

[MKR]

I say it depends on your vehicle, In my f150 I can not tell any difference between 5w-30 and 20w-50. In my car I can feel a big difference between the two. I can't feel any difference between 5w20 and 5w30 though.

 

[Gary Allan]

Yes, Ugly3

The difference can be felt when your talking that big a difference. The colder it is ..the more you can perceive it. I don't perceive/express it as a sluggish thing. "Tight" would perhaps be a good term. Not unlike what I used to feel with a true high compression engine at lower throttle openings.


However, I'll also say that in long/highway mileage there was barely a difference ..while short mileage difference was substantial. If I wasn't pushing a minivan shoe box @ 70+mph ..long mileage differences may have been enough to accurately measure. I actually got a little better with the 20w-50 then 5w-20 in back to back long trips. Normal error could surely have masked any advantage of the lighter oil. It's just easier to measure on the short trip cycle ..at least for me.

 

[Volvohead]

In a turbocharged engine, viscosity absolutely makes a difference. Viscosity past a certain point will begin to slow spool up, which can become quite noticeable.

Otherwise, I most notice heavier viscosities during extreme cold weather starts.

 

[427Z06]

Quote:

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I feel the difference between 5w30 and 5w20 even when its fully warmed up, but only at small throttle openings. 15w40 big difference. 10w30 can't tell from 5w30.

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Bingo! A couple of horsepower won't be noticed when at WOT making maximum power, but at part throttle, like say 20 horsepower, that 2 hp is now 10% of what's available at that throttle setting. YMMV.

 

[KJA426]

My Dodge 4.7 feels much peppier on 30 weight compared to 40 weight.

 

[Fordiesel69]

So in a Ford modular engine such as in my crown vic, (4.6L) will using GC 0w-30 really make it feel that much more sluggish then using 5w-30? I really want to give it a try however folks report their f-150's being real sluggish.

 

[AndyH]

Quote:

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So in a Ford modular engine such as in my crown vic, (4.6L) will using GC 0w-30 really make it feel that much more sluggish then using 5w-30? I really want to give it a try however folks report their f-150's being real sluggish.

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I say try it and see what you think, each engine responds differently. It appears from my reading these "GC makes my engine sluggish" posts that most people that feel that way are driving smaller 4-cylinder N/A engines.

 

[toocrazy2yoo]

My teeny little 1.6 in this 05 AccentGT just went from GC to QS 4x4 Syn (clear bottle) 5W20 and it's been pretty cold the last few mornings. I can tell no difference in cold start-up, or hot running (whether this thing even GETS hot is open for discussion), noise and/or tapping is nonexistent. No discernable decrease in MPG either. Perhaps there's a miniscule difference but I'm not seeing it. This has been the case whether on Havoline 5W20, or the 10W30 PP from the Home Depot giveaway this summer. No difference..

 

[Drew99GT]

Last year I had a 50/50 mix of 10w-30 and 20w-50 in my car. One morning in late fall, it got to about 15 degrees here, and my car made a GAWDAWEFULL racket when I coasted down my hill in 2nd gear after cold first start. A switch to 5w-30 and it was whisper quiet.

 

[Junior]

Quote:

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So in a Ford modular engine such as in my crown vic, (4.6L) will using GC 0w-30 really make it feel that much more sluggish then using 5w-30? I really want to give it a try however folks report their f-150's being real sluggish.

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I never noticed any difference in my 5.4 bewteen 5w20 and 15w40 during normal driving. Noticed a differnce in cold weather starting but that is it.

 

[427Z06]

Quote:

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Code:

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Viscosity in cSt

TEMP GC Havoline

C F 0W-30 5W-30

0 32 517 573

10 50 280 293

20 68 163 165

30 86 102 100

40 104 67 64

50 122 46 44

60 140 34 31

70 158 25 23

80 176 19 17

90 194 15.0 13.5

100 212 12.1 10.8

.

VI Index 179 159

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I believe your Gold GC numbers are a bit off. Further, this comparison is a bit unfair comparing a dino to a full syn, but non-the-less let's look at another comparison.

Code:

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T(C) TA 5w30 * Gold GC 0W30

0° 549 552

10° 286 295

20° 162 170

30° 99 105

40° 64.0 69.0

50° 43.6 47.4

60° 31.0 33.9

70° 22.9 25.2

80° 17.4 19.2

90° 13.6 15.1

100° 10.9 12.1

HTHS 3.1 3.6

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Note that Kinematic Viscosity alone doesn't tell the whole story. The HTHS is bigger contributor to the frictional drag created at all the bearings and other high shear areas of the engine.