Viscosity Of Various Oils at 68 Degrees

[c_rossman]

I just conducted a flow test of oils thru a hole bored in a piece of aluminum. The test was conducted to compare cold start properties in the somertime of the upper midwest. Here are the verious oils tested and times it took for one ounce of oil to flow thru a .1 inch of a hole.

Mobil1 5w30-1:08
Mobil1 5w40SUV-2:01
Mobil1 10w30-1:20
Pennzoil 5w20-0:52
Pennzoil 10W30-1:34
Pennzoil 10w40-2:06
Pennzoil HD30-2:23
ChevronDelo 15w40-2:39
Mobil Delvac15w40-2:46
Mystik 10w30 CH-4-1:27
Supertech ATF-0:40
Supertech 85w140GL5-10:36

I am very disappointed in the Mobil1 SUV 5w40. Pennzoil 10w40 isnt far behind, It is just a bit thick when at room temp. I ran the test 2-3 times on each oil making sure the times were consistant. All oil bottles were on the same shelf in an airconditiond shop at 68 degrees.

[ August 13, 2004, 02:55 PM: Message edited by: Dan4510 ]

 

[honus402]

I'm not a Pennzoil fan, but it looks like the Pennzoil 10w-30 looks pretty good. The Delo 15W-40 (my fav), doesn't seem to make the grade. Maybe 10W-30s are the best overall weight. I think I'll try to locate some Delo or Delvac 10W-30 for the next change in my Crown Vic.

 

[c_rossman]

I would like to test oils at 32 degrees too, but I am not sure how accurate the tests would be without the entire room or testing device at 32. I am thinking the Mobil1 5w40 will be thinner than 10w30's when cold but who knows. I like the Mystik diesel rated 10w30 for flow, It flows better than the Pennzoil with a better add pack.I found the stuff at a local Fleet Farm in gallon jugs for $4.79. I use it in my Honda ATV. I was using Pennzoil for a few changes. It seems to shear out of grade after about 2000 miles, my oil pressure would drop when hot.

[ July 18, 2004, 07:47 PM: Message edited by: c_rossman ]

 

[labman]

Great test. Similar to the common viscosity cups widely used. As long as everything had been at the same temperature for a while, should be valid. I like to see numbers like those, not opinions.

Maybe you could let everything set outside in the winter and then run the test.

 

[TallPaul]

quote:

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Originally posted by c_rossman:
It seems to shear out of grade after about 2000 miles, my oil pressure would drop when hot.

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So was it that the hot oil pressure held well for about 2000 miles and then you were seeing lower pressure under the same conditions? I am very interested in whether oil pressure is a good indicator of permanent viscosity collapse.

 

[XS650]

quote:

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Originally posted by c_rossman:
I would like to test oils at 32 degrees too, but I am not sure how accurate the tests would be without the entire room or testing device at 32.

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Nice work!

Here's how you do it at 32F. Put the bottles of oil in the fridge for a day to get them close to freezing. About 38F for a typical fridge.

Then take them out and let them sit in icewater with a lot of ice in it for an hour. That will be a well regulated 32F. A large picnic cooler would be a good container.

Modify your vicosity device so it is surrounded with icewater while you are running you tests. You could put it inside another cup and glue it to the bottom with a large hole in the bottom of the outer cup so it doesn't add restriction to the oil flow. The icewater in the outer cup will keep your viscosity cup at a constant 32F.

 

[c_rossman]

I have a Ford 460 V8, do some moderate towing. Normal hot oil pressure at idle is about 40 psi, after 2000-2500 miles I notice about a 15psi drop in pressure hot(25psi). I change the oil and all is back to normal. I am running Delo400 15w40 right now, but there is only 1500 miles on it. It is just a bit thick for this motor. I have noticed the shearing effect of Supertech 5w30 bigtime after 2500 miles, I thought 10w30 would help but not as much as I thought. Maybe these 460's are just hard on oil. Anyone else gauge oil changes on oil pressure drops like I do?

 

[Motorbike]

quote:

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Originally posted by c_rossman:

I am running Delo400 15w40 right now, but there is only 1500 miles on it. It is just a bit thick for this motor.

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Take it down to the Equator and things will be better

The actual width of the 460 crank journals both rod and main are the largest of any domestic automobile engine I've seen . After market cranks for performance and or racing actually are re-sized for the big block Chevy bearings . There is just too much surface to lube properly at higher RPM .

5w-40 group III PCMO synthetics with a VI of around 80 @40c would make for a nice year round choice in these engines due to how they oil unless they lived in the far North . 5w-30 Maxlife winter and possibly 10w-40 Maxlife or simalar oils in summer would be good second choices especially if towing .

PS , Thanks for the bench test showing how thick some of these oils actually are . Getting a drill motor smoking hot while hand priming a race motor with thick goo tells alot too

 

[Blue99]

I re-organized the samples by flow rate.

code:

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Supertech ATF 0:40

Pennzoil 5w20 0:52

Mobil1 5w30 1:08

Mobil1 10w30 1:20

Mystik 10w30 CH-4 1:27

Pennzoil 10W30 1:34

Mobil1 5w40SUV 2:01

Pennzoil 10w40 2:06

Pennzoil HD30 2:23

ChevronDelo 15w40 2:39

Mobil Delvac15w40 2:46

Supertech 10:36

85w140GL5

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What’s interesting is how the 40 weight oils split into 2 groups. The 15W-40’s are definitely thicker than either the 10W-40 or the 5W-40SUV synthetic.

The multi-vis 30 weights flow twice as fast as the Pennzoil 30 HD!

 

[TallPaul]

quote:

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Originally posted by c_rossman:
I have a Ford 460 V8, do some moderate towing. ...

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I recently posted a UOA on my Ford 460 V8 motorhome (27', about 10 - 11 thousand pounds loaded). UOA was 4400 miles on Maxlife 10w30. Lab said the oil thickened to a 40 wt, but my oil pressure did not go up correspondingly (I suspect the lab goofed). I am consistently getting about 70 psi cold, 58 psi hot at 2000 rpm, and aroudn 25-30 hot idle with this motorhome.

 

[c_rossman]

I want to try some Mobil1 0w30 or 0w40, I just hate spending that kind of money for an oil change. I am the type of guy to change oil every 3000 miles. Yes synthetic oils are better but they get just as dirty just as fast as the cheap stuff, but sythetics are better at controlling that. The oil pressure drop doesnt bother me a whole lot, the oil is probably still fine. I have 7 quarts of pennzoil laying hear and a Napa gold filter(1773)Big Version of the FL1A. The whole point of this test is to prove even in the summer, Xw40 oils are thicker and do not flow as good as the Xw30's

 

[XS650]

quote:

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Originally posted by c_rossman:
The whole point of this test is to prove even in the summer, Xw40 oils are thicker and do not flow as good as the Xw30's

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The question is, does it matter within the limits you are seeing. Since oil in an angine is pumped, I seriously doubt it. Interesting tests though.

 

[labman]

Oil is relatively Newtonian, that is the viscosity is about the same at different shear rates, and shear history. Not true with some of the stuff I worked with in the paint industry. Some resins were tested at more than one shear rate with a Brookfield viscometer. Many of them also quickly sheared down temporarily, recovering when allowed to stand. The cup, efflux, style viscosity meters sometimes give very poor data for spraying paint, but should be fairly good for oil.

 

[Steve S]

Remember that once the oil is at the output of the pump it will get to the top end quick. The engine killer is when the oil takes a long time to get up to the pump. C_rossman thanks !!! for the test.

 

[c_rossman]

The oil pressure sensor on a 460 V8 is on the tail end of the oiling system, I noticed no difference in times it took for oil pressure to read on the gauge between 5w30 and 15w40 when cold. I am just worried about the cam shaft and cylinders because they are splash lubricated. The thicker oil at low RPM's will not be thrown off the crank as well as a thinner oil.I guess they say that most if not all wear occurs at cold start. Another way to look at it, is that a thicker oil will stay in the oil gallies longer than a thinner oil.

 

[Ded Mazai]

Interesting test but totally useless. It does not prove anything in regards to oil starvation. Since all automotive oil pumps are positive displacement pumps, they pump exacly the same volume of oil per revolution no matter what oil you use.

 

[427Z06]

quote:

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Originally posted by Ded Mazai:
Since all automotive oil pumps are positive displacement pumps, they pump exacly the same volume of oil per revolution no matter what oil you use.

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True, but all oil pumps also incorporate a bypass valve. Above a certain pressure and it'll start bypassing oil back into the pan, thus viscosity has some influence on how much oil actually circulates thru the engine.

 

[labman]

quote:

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Originally posted by c_rossman:
The oil pressure sensor on a 460 V8 is on the tail end of the oiling system, I noticed no difference in times it took for oil pressure to read on the gauge between 5w30 and 15w40 when cold. snip....

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Pressure travels at the speed of sound, but thick oil flows much slower. An oil that takes over twice as long to flow in your test, will have less than half the flow at the same pressure. Pressure at the tail end of the oil system doesn't mean most of the oil isn't going through the bypass directly to the pan.

It has been years since I adjusted solid lifters on a hot running engine. Might be interesting to try starting a cold engine with the valve cover off with various weights of oil in it. How many modern engines will even run with the valve cover or cam cover off?

 

[EmbarkChief]

quote:

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Originally posted by labman:

quote:

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Originally posted by c_rossman:
The oil pressure sensor on a 460 V8 is on the tail end of the oiling system, I noticed no difference in times it took for oil pressure to read on the gauge between 5w30 and 15w40 when cold. snip....

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Pressure travels at the speed of sound, but thick oil flows much slower. An oil that takes over twice as long to flow in your test, will have less than half the flow at the same pressure. Pressure at the tail end of the oil system doesn't mean most of the oil isn't going through the bypass directly to the pan.

It has been years since I adjusted solid lifters on a hot running engine. Might be interesting to try starting a cold engine with the valve cover off with various weights of oil in it. How many modern engines will even run with the valve cover or cam cover off?

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LOL, not many I'm sure

 

[Ded Mazai]

quote:

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Originally posted by 427Z06:

quote:

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Originally posted by Ded Mazai:
Since all automotive oil pumps are positive displacement pumps, they pump exacly the same volume of oil per revolution no matter what oil you use.

---

True, but all oil pumps also incorporate a bypass valve. Above a certain pressure and it'll start bypassing oil back into the pan, thus viscosity has some influence on how much oil actually circulates thru the engine.

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Yes, agreed. When it is very cold for a specific grade of oil then the bypass valve opens before the oil fills up the system. This is a pretty bad situation but it has nothing to do with the current test setup and the achieved figures because it is just not cold enough. The chances are that both 5W-20 and 5W-40 will perform very similarly at low temperature.

And another thing. The oil pressure builds up almost instantly as soon as there is no air in the oil passages. Not sooner, not later. And because the oil flows at a constant rate for any grade of oil there will be no difference how soon the pressure gauge shows something.