Here are the data for the viscosity calculations. I tried to pick combinations that replicate common mixing practices seen on BITOG. The first is the classic 50:50 Mobil 1 0w-40 and 0W20. The rest simulated adding a quart of heavier oil to thicken things a bit, or a quart of thinner oil to thin things down a bit. There is also the practice of adding a quart of Redline as an “additive”. Other mixes are intended to test the equations with differing base stocks and viscosity ranges.

As you can see, the measured viscosity varied significantly from the published “typical” viscosity in some cases. The data came from U.S.A. region PDS sheets published directly on the oil manufacture’s web site. In the case of Castrol, the sheet for the GTX 20W-50 was dated 2012. The data for the Valvoline SAE 30 ND was from 2006, which was current when the oil used was purchased. The other oil’s data are current.

These are the calculations I’d like to see run at a minimum:

Widman measured cSt.

Widman PDS cSt.

Gokhan’s calculator measured dynamic viscosity, estimated alpha from tables in calculator(state number used).

Gohkan’s calculator measured cSt., alpha 1.0 for all.

Gokhan’s calculator measured cSt., estimated alpha from tables in calculator(state number used).

Gokhan’s calculator PDS cSt., alpha 1.0 for all.

Gokhan’s calculator PDS cSt., estimated alpha from tables in calculator(state number used).

Those combinations will allow us to see how much error is introduced by the difference in a measured viscosity vs, typical, the calculation methods, and the effect of adding an estimated alpha into the equation. Once all the data has been posted I’ll post the measured values for the mixes. At that point, someone who likes to play with Excel can wrap it all up in a neat, informative table.

The oils:

Oil (Measured

[email protected]) [PDS

[email protected], PDS density g/

[email protected]]

Mobil 1 0W-20 EP(8.18) [8.6, 0.839]

Mobil 1 0W-40 FS (11.73) [12.9, 0.8456]

Castrol GTX 5W-30 ULTRACLEAN (9.56) [11.0, 0.862]

Castrol GTX 20W-50 (17.21) [18.09, 0.884]

Redline 50WT Race Oil (17.29) [19.2, 0.897]

Valvoline SAE 30 ND (10.86) [11.0, 0.889]

Rotella T5 10W-30 (11.34) [12, 0.869]

The mixes:

Oil 1(fraction) - Oil 2(fraction)

1. Mobil 1 0W-20(0.5) - Mobil 1 0W-40(0.5)

2. Mobil 1 0W-20(0.2) - Mobil 1 0W40 (0.8)

3. Mobil 1 0W-20(0.8) - Mobil 1 0W40(0.2)

4. Castrol GTX 5W-30((0.2) - Castrol GTX 20W-50(0.8)

5. Castrol GTX 5W-30((0.8) - Castrol GTX 20W-50(0.2)

6. Mobil 1 0W-20(0.5) - Redline 50WT Race(0.5)

7. Mobil 1 0W-20(0.2) - Redline 50WT Race(0.8)

8. Mobil 1 0W-20(0.8) - Redline 50WT Race(0.2)

9. Mobil 1 0W-40(0.2) - Redline 50WT Race(0.8)

10. Mobil 1 0W-40(0.8) - Redline 50WT Race(0.2)

11. Castrol GTX 5W-30(0.5) - Rotella T5 10W30(0.5)

12. Mobil 1 0W-20(0.2) - Castrol GTX 20W-50(0.8)

13. Redline 50WT Race(0.5) - Valvoline SAE30 ND(0.5)

Ed