A viscosimeter is a device used for measuring the viscosity of an oil and is generally __________ accurate.

• A. 90%-95%
• B. 95%-99%
• C. 99%-100%
• D. 80%-90%

Answer: (B)

Measuring viscosity needs results you can trust, because how thick or thin a oil is directly affects lubrication and protection of engine parts. A viscosimeter gives high-precision readings when it’s properly calibrated and used under controlled conditions, especially with stable temperature.

That’s why the typical accuracy falls in the 95% to 99% range. In practical terms, the instrument’s reading is within a few percent of the true viscosity, which is what you want for reliable oil specification, quality checks, and performance predictions. Calibration against standard oils and keeping test conditions consistent—especially temperature—are what keep this level of precision achievable.

Lower accuracy ranges would mean more variability and less confidence in the results, while near-perfect accuracy (99%–100%) is rare in routine testing due to real-world factors like temperature fluctuations and sample variation.