After seeing the improvement the Redline D6 made in the 6F35 unit in our Fusion, I've decided to do yearly drain/fills with Redline products in both of our cars. For the Fusion, it's D6 all the way. For the Focus though, which recommends Mercon V, the D4 fluid matches up most closely. However, the 08-11 Focus, while mechanically identical to my 07, recommends Mercon LV instead of the Mercon V my Focus does. I never understood why the 05-07 Focus wasn't 'upgraded' to the LV spec, since the automatic trans units used in 05-11 were all exactly the same
So, simply put... Mercon V = use D4, Mercon LV = use D6. I'm debating which one I should use though. The D6 is all-in-all a higher quality fluid than the D4, and is slightly more shear stable. The operating viscosity of the D4 is 7.5 (as is Mercon V), whereas the D6 is 6.1 (as is Mercon LV). I have used Maxlife ATF in the Focus before, the newer formulation, which also has a 6.1 operating temp viscosity. So I'm sure the D6 would still do very well, I'm just wondering if it'd do better than the D4. Any thoughts? Thinner fluid in the cold will make for better shifts, too. At least I think it will...
So, simply put... Mercon V = use D4, Mercon LV = use D6. I'm debating which one I should use though. The D6 is all-in-all a higher quality fluid than the D4, and is slightly more shear stable. The operating viscosity of the D4 is 7.5 (as is Mercon V), whereas the D6 is 6.1 (as is Mercon LV). I have used Maxlife ATF in the Focus before, the newer formulation, which also has a 6.1 operating temp viscosity. So I'm sure the D6 would still do very well, I'm just wondering if it'd do better than the D4. Any thoughts? Thinner fluid in the cold will make for better shifts, too. At least I think it will...