Homemade viscometer anyone?

[Ler]

I was thinking about my motorcycle the other day, which naturally led me to think about oil. My thought is, in certain use conditions it seems reasonable that the oil has sheared to a lower viscosity before additive depletion/exhaustion. In that case, determining the right service interval depends on first finding out how long an oil can stay in grade, then performing the hair-splitting analyses that we're so fond of.

From that, I began to see the utility in a cheap, crude viscometer.

Falling ball viscometer, Cole-Parmer, $180

Falling ball viscometer, Homemade, $1.08

Fill with test fluid, toss in boiling water for a bit, then measure the elapsed time for the ball to fall a fixed distance. Use a couple of fluids of lesser and higher known viscosity to calibrate, then interpolate.

Anyone have experience with something like this? Care to share experience, or suggestions for calibration fluids?

 

[Shannow]

Great work.

 

[Merkava_4]

I've used a #2 ZAHN cup for measuring the viscosity of paint; that's an extremely useful tool.

 

[blueiedgod]

New guy here. Have been reading for a while... This is the best post ever! lol


I just use Brookfield viscometer at work. We also have a TA Rheometer as well.

 

[Jim]

Someone correct me if I am wrong but I think the shearing effects need to be tested at high temperature. If you can test it at 100C it would be useful.

 

[surfstar]

Well if the VII are getting sheared, that should also affect cold start viscosity, right?

Either way the test must be done at a similar temp to the reference oil. Best way would be to keep some of the original oil for control/reference, and test at various temps (freezer, room, hot).

 

[Jim]

My understanding of VI improvers is that they function by molecules unwinding when they get hot. I don't think they do much at lower temps. These are the molecules that are broken by high loads and shearing.

 

[Ler]

The point about throwing into a pot of boiling water for a bit was to suggest that tests would be run at a (fairly) uniform 100C, the standard for testing 'hot' oil viscosity. The real issue here is getting fluids of known viscosity for calibation. Yes, I could buy calibration fluid, but that would destroy the homemade hack job charm of this project.

 

[surfstar]

Quote:

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Yes, I could buy calibration fluid, but that would destroy the homemade hack job charm of this project.

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Just compare it to the same oil, unused. That way you can see how much it sheared vs the original oil, percentage wise, then you could crudely calculate the visc of the used oil.

Jim, you're right - pour point depressants would affect the cold visc, not VII