What is Viscosity?
Viscosity is a measure of a fluid's "thickness" or resistance to flow. Low viscosity (water) flows easily; high viscosity (molasses) flows slowly.
Dynamic vs. Kinematic
- Dynamic Viscosity: Measured in Poise (P) or Centipoise (cP). Water is roughly 1 cP.
- Kinematic Viscosity: Measured in Stokes (St) or Centistokes (cSt). This takes the fluid's density into account.
Why Oil Viscosity Matters
If your car oil is too thin (low viscosity), it won't protect the engine. If it's too thick, it won't reach the parts that need it during a cold start.
Key Takeaways
- Temperature changes viscosity (heat makes liquids thinner)
- SAE 5W-30 is a measure of oil viscosity
- Centipoise is the most common unit in industry