These are the calculations I'd like to see run at a minimum: The data for the Valvoline SAE 30 ND was from 2006, which was current when the oil used was purchased.

In the case of Castrol, the sheet for the GTX 20W-50 was dated 2012. region PDS sheets published directly on the oil manufacture's web site. Other mixes are intended to test the equations with differing base stocks and viscosity ranges.Īs you can see, the measured viscosity varied significantly from the published 'typical' viscosity in some cases. There is also the practice of adding a quart of Redline as an 'additive'. 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. The first is the classic 50:50 Mobil 1 0w-40 and 0W20. I tried to pick combinations that replicate common mixing practices seen on BITOG.

Here are the data for the viscosity calculations. Here are the average alpha values for Ed's samples, with the info in the parenthesis showing the approximate oil composition:

Once you know the alpha for a given sample, you can calculate the viscosity for different fractions of the same two oils using: n1, n2, and n are the viscosities of Oil 1, Oil 2, and Mix, respectively. If you want to calculate the alpha for a given sample directly without trial and error, here is the formula:Īlpha = / (4) You need to have at least one measured sample to calculate the alpha empirically, from which you can calculate the viscosity for different mix ratios for the same two oils. (3) alpha values ranged from 0.42 to 1.46 in Ed's samples, greatly deviating from the Arrhenius equation and Widman mixing calculator, which assume alpha = 1. (2) Arrhenius equation and the Widman mixing calculator do not work! (1) Lederer - Roegiers equation when used with the proper alpha value works!

Cross reference between API Degrees, specific gravity, etc.I have finally got to calculate the empirical alpha values using the Blackstone KV100 for Oil 1, Oil 2, and Mix.ISO viscosity ranges : The DIN 51519 table.Transmission oil viscosity ranges : The SAE J306 table.Engine oil viscosity ranges : The SAE J300 table.Viscosity Equivalency table between SAE, ISO, SUS y AGMA.The next section contains calculators where you can actually determine the viscosities or variations on specific products in specific operating conditions. This section contains several tables that are useful in looking up ranges for different categories of oils, their weight relationship and viscosity variations throughout different temperature ranges.

Widman viscosity index calculator