Obviously you did not follow the posts a few years back when I introduced ATF+3 to this group. I studied it as well as I could, including asking the oil company reps that called on me to see if they could get some technical advice as to if there would likely be a problems with ATF+3 with it's higher level of friction modifier.

Although they would not come right out and endorse it, they did say that it would probably work fine. After all, it was used in Chrysler product manual transmissions. Much to my surprise, the shifting quality improved tremendously over using Mercon.

I continued using ATF+3 from about 45,000 miles until 150,000 miles when I installed the Ford Honey (I just checked my log, so it has been in 60,000 miles, not 40,000 as I posted a few minutes ago). Prior to using ATF+3, the fluid change using Mercon improved shifting somewhat, but the improvement was short lived.

The immediate impression of the Ford honey + XL3 was that there was a slight improvement over ATF+3, but not much. As time has gone on, the improvement has gradually continued to increase.

ATF+3 and ATF+4 are nearly the same, but ATF+4 has a higher synthetic blend and a greater temperature range. Both have the same level of friction modifier. Both are used on Chrysler product manual transmissions.

From what I have been able to learn, ATF+4 is very similar to Mercon V, but does have a somewhat higher level of friction modifier. Mercon V does have a higher level of friction modifier than Mercon.

Because Chrysler was slow in releasing a license for other companies to make ATF+4, Mobil, and some others, actually recommended that their Mercon V product be used in Chrysler products that called for ATF+4. This is likely to change because Chrysler recently announced that they will license others to sell ATF+4. It is interesting that Mobil is the vendor that supplies Chrysler with ATF+4.

The explanation about why friction modifier often works well in manual transmissions is that it helps the synchros clear off the oil in the mating surfaces of the synchros better, allowing better bite without being harsh. I don't know how accurate this is. There seems to be some concern that too much friction modifier may actually weaken the lubrication ability and lead to gear damage. It must be remembered though, that in it's primary role as an additive, it is used in differentials with limited slip clutch packs, where gear wear is even much more critical.

Jim Johnson 98 SVT 03 Escape Limited