Screwdriver viscosity test: Mobil 3309 is not OE ATF

[vtl]

Did that simple viscosity test few minutes ago:

Aisin is thinner. Color and smell is about same, Mobil may be a bit more saturated.

That aligns with my feeling that transmission shifts more harsh with Mobil 3309.

[oragex]

While pretty much everybody seems to agree that Aisin, Toyota Type-IV and Mobil 3309 are the same, there might be differences between them. Perhaps, they all meet the 3309 norm, however other properties might be different. I tried the Valvoline Max life (also 3309 norm) and it seemed to me thinner. I also had the Mobil 3309 and - while this is purely subjective - I felt it was shifting harder than the Toyota Type-IV (which I'm using now). However, my solenoids are not in the best shape, perhaps with better solenoids I wouldn't feel a difference.

[vtl]

I had same feeling on both my wagons: with Mobil transmission shifts hard.

[packetfire]

I think that the screwdriver test would not be as reliable as a test where the fluids dripped through the same pinhole in the bottom of the sames shotglass-sized container that was filled to the brim with each.

Many many moons ago, I worked in the darkroom of a printing house as a summer job, shooting artwork, making color separations, and making printing plates. Ink viscosity was a big deal to the pressmen, and they had a simple system with a metal ladle that had a small hole, and a stopwatch. They would dip the metal ladle into the ink, and time how long the ink took to run out of the hole.

This might be a better low-tech viscosity testing set-up, as it will be a better test than allowing an unknown volume of oil to drip in each drop.

My "problem" with the screwdriver test is that both viscosity AND density come into play here, and there is no way to objectively measure the thickness of the oil film on the surface of the screwdriver as it is withdrawn.

The thickness of the film can be approximated by this equation (which mattered to printing plate makers, as it defined the amount of detail that could be printed with any specific ink):

t = SQRT( 2vn/pg )

where:
t = the thickness of the (ink or oil) film on the withdrawn object (the screwdriver)
v = the speed of the withdrawal from the ink or oil
n = the absolute viscosity of the ink/oil
p = the density of the liquid
g = acceleration due to gravity

(It is scary that I have not found something more interesting to fill that part of my memory in the decades since I last needed that equation...)

All things being otherwise equal, you can see that viscosity in on the top of the division, while density is on the bottom. And we know that a denser liquid will drip off faster because an equal volume will have more mass, so you can see how a denser liquid might appear to have less viscosity simply because it would drip off faster, or in larger drips. You may be looking at two fluids with identical viscosity, but different densities.

So, does the screwdriver test measure viscosity or density? It is a gestalt measure of BOTH at the same time.

If you had some graduated cylinders of the sort used in Chemistry class, and a super-accurate drug-dealer scale, you might be able to compare the weight of equal volumes of each oil, but these measurements are likely best left to someone who works in a lab every day, as there will be more variation from the scale used, and the eye-balling of the liquid level in the cylinders than anything else.

[vtl]

Screwdriver test is indeed imprecise, but even that shows clear difference between these two ATFs.

Also, what is more important, dumping sump of transmission and filling it with Aisin resulted in a shifts quality which I last felt when the car was bought 3.5 years ago, and it was still filled with OE ATF. This is even more important indication to me than dripping screwdriver

Mobil still can be the maker of Aisin ATF, but it's not exactly the same fluid as their 3309.

$6.9/quart @ autohausaz + free shipping.

[zanzabar]

Or you could actually look up real viscosity measurements:
Mobil 3309/ Toyota T-IV: @40C= 33 cSt; @100C = 7.1 cSt
Mobil 3324/ Toyota WS: @40C= 23 cSt; @100C = 5.3 cSt
Aisin TIV: @40C= 34.88 cSt; @100C = 7.332 cSt
Eneos Eco ATF:@40C= 27.67 cSt; @100C = 5.73 cSt

So, in other words... Aisin is not thinner.

[abscate]

Tribology trivia..

The screwdriver test was developed by Philips Petroleum, Shirley...

[zanzabar]

Has anyone tried the lower viscosity ATFs like Toyota WS/Mobil 3324? What was your experience?

I'm considering using the Eneos stuff in mine, just a single drain and fill so it'll be a mix of Eneos and 3309 - viscosity will thus be intermediate between the two... about @40C= 30 cSt; @100C = 6.3 cSt. I think this Eneos is higher quality and because of the lower viscosity I'm hopeful of better mpgs with same or better wear protection.

[vtl]

So, in other words... Aisin is not thinner.

Look at the video: when a screwdriver was soaked in at the same depth, Mobil drips slower, at the same temperature. I forgot everything I've learned 15 years ago about kinematics of fluid, but this "Philips Petroleum" (c) abscate test is not far away in terms of result from a real lab test.

[zanzabar]

So, in other words... Aisin is not thinner.

Look at the video: when a screwdriver was soaked in at the same depth, Mobil drips slower, at the same temperature. I forgot everything I've learned 15 years ago about kinematics of fluid, but this "Philips Petroleum" (c) abscate test is not far away in terms of result from a real lab test.

C'mon guys. What is this, the Donald Trump school of tribology?

Not that I am an expert in this stuff, but dripping off of a screwdriver obviously has little to do with viscosity measurements that describe a fluid's behavior inside an engine or transmission. The difference from what I gather from the googles is between kinematic viscosity (screwdriver test) and absolute viscosity (real measurement).

http://www.machinerylubrication.com/Rea ... -viscosity