Hello,

I just had my used oil checked in the power station laboratory for viscosity.
The oil is 0w40 Mobil 1 and done 5000Kms in 7 months.
I have found out that the viscosity is 12cst@100degC and 60cst@40degc.
I have also checked a fresh oil sample and the viscosities are 12.8cst@100degc and 68cst@40degc.
The oil specifications from Mobil are 14.8Cst@100degC and 84cst@40degC.

Any commends please.

Well, oils are a mixture of base oils and additive packages. Sometimes the oils are "thinned out" - they have less additive package than the should have. This may have an influence of the viscosity, too.

But it could be vice versa, too. The additive package is O.K., but the amount of PAO 6 is not sufficient.

But these are just assumptions, your viscosity measurement device is definetelly O.K?

The instrument is ok.
I have got in touch with Mobil but no answer yet

Viscosity of the fresh oil (12.8/100degC and 68/40degC) is really too low for the SAE 0W-40 viscosity class oil.
Generally, viscosity decrease during oil operation is common. It is caused by shear unstability of the viscosity modifiers. Drop of viscosity can be noticeable, especially for the 0W-40 oils, which contain a high portion of viscosity modifiers.

quote:

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Originally posted by Frixos:
Hello,

I just had my used oil checked in the power station laboratory for viscosity.
The oil is 0w40 Mobil 1 and done 5000Kms in 7 months.
I have found out that the viscosity is 12cst@100degC and 60cst@40degc.
I have also checked a fresh oil sample and the viscosities are 12.8cst@100degc and 68cst@40degc.
The oil specifications from Mobil are 14.8Cst@100degC and 84cst@40degC.

Any commends please.

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I read all forum members comment. I suggest that if you still have fresh oil sample, please get it tested from an independant lab. For a 0W 40 oil SAE viscosity range is 12 to 16.5. Mostly oil companies keep mid point as blend control. In Mobil case also I could notice the mid point control (14.8 CST @ 100 C). Your power station lab result is not at all near to mobil specification value. Let us have the independant lab result, then discuss.
Kumar
kumartr2@yahoo.com

quote:

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Originally posted by Frixos:
Hello,

I just had my used oil checked in the power station laboratory for viscosity.
The oil is 0w40 Mobil 1 and done 5000Kms in 7 months.
I have found out that the viscosity is 12cst@100degC and 60cst@40degc.
I have also checked a fresh oil sample and the viscosities are 12.8cst@100degc and 68cst@40degc.
The oil specifications from Mobil are 14.8Cst@100degC and 84cst@40degC.

Any commends please.

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Frixos, you are holding back information that is required in order for people here to assist you in coming to an understanding on what you are seeing re: lower that spec viscosity. It could be something as simple as a bit of fuel dilution. Why don't you get a full analysis and post the results and let the forum discuss the issue?

regards......

quote:

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It could be something as simple as a bit of fuel dilution.

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I thought the same at first, but this cannot be with a fresh oil sample...

Frixos,
You should get the oil tested for viscosity at some other lab too for crosschecking. Might be your lab has got some error in the temperature controlling mechanism or thermometer which is showing lower than the actual temperature of oil bath. might be, just a possibility that your lab is giving viscosity at 45 degree and 105 degree unkowingly. Please get it checked, there may be a difference in viscosity of new oil and used oil due to fuel dilution, but there should not be such a large variation between new oil and catalogue specification. Please also make sure that you have got the oil from genuine dealer and it is not rerefined oil.

Hello,

Our lab uses the latest technology equipment.
We test heavy fuel and turbine oils for some time now.
I did not bother to send a sample to an independent laboratory,instead I stopped using Mobil 1.