Wow, in thermal conductivity of synthetic vs. mineral oil, synthetics do have a higher thermal conductivity. As the synthetic oil carries away slightly more heat, and drips down into the sump, the anti-freeze coolant will get a little less heat, not more.
Originally Posted By: MolaKule
Synthetic lubricants have a slightly higher thermal conductivity than do their mineral oil counterparts.
The calculations below were done for a majority PAO lubricant verses a mineral oil:
Originally Posted By: From Mola's 7/02 thread
Using the Heat Conduction formula:
H = kA(To-Ti/L),
where H is heat Power in W.m, k is heat conduction coefficient in W/meter-squared/C, and temps in C. The k for synthetic oil is 0.16 and k for dino is 0.128, To is temp out of a journal bearing = 100 C, and Ti was oil temp into bearing = 80C, representing a temp rise of 20C, which is a rule of thumb. L is the thickness of the oil film which is on the order of 1um at high loads. A is area of film assumed to be a patch of area of 1 mm squared.
Hs = conductive heat transfer of synthetic oil in W = 3200 W,
Hd = conductive heat transfer of dino (mineral oil) in W = 2560 W.
Therefore, synthetic oil is 20% more efficient at conductive heat transfer than mineral oil.
The same film thickness for both dino's and synth's was used for the calculations.
Also see:
Gear Tribology and Lubrication II
