And where's your DATA to support that, rideahorse?
Use what the manufacturer recommends here... which is a good mineral oil, without friction modifiers.
Q: What kind of oil should I use? Can I use synthetic? Do I need friction additive/modifier?
A: A quality petroleum/mineral based oil works best in the Truetrac units. We do not recommend synthetic oil. Friction additive/modifier is not required.
Huh. I have had a Truetrac in my 4runner for about 100k miles.
I used conventional for breakin, and boy did it get hot!
After 50 miles or so, I put in Redline, (Which immediately ran much cooler) and that is what I have used ever since.
No mention at the time of installation that synthetic was not recommended.
It works great, but maybe it would work even better with mineral?
The entire rear end depends on the diff lube; gears, limited-slip, wheel/axle bearings, pinion bearings. Do I use what's best for one component (LSD) at the expense of the rest of the components?
As I understand it, the synthetic lube does not hurt the Tru-Track, it just doesn't allow it to lock up as readily....which should, in theory anyway, make it last longer.
I have a TrueTrac and I use the Redline NS gear oil. So it is synthetic but does not have the "limited slip" friction modifiers.
I guess if the oil is too "slippery" the torque bias of the unit is reduced.
In the past I have used various other oils with friction modifier and the unit still seemed to work properly. I don't think a friction modified oil would hurt the TrueTrac... I don't see how that could be possible.
I have been beating on my 12 bolt TrueTrac for 7 years running nothing but Red Line Heavy Shockproof gear lube with zero issues. Power is provided by a 700hp 496 with a Tremec 6 speed and with a set of sticky M/T DOT cheater slicks, it has easily handled all the abuse I've thrown at it. Differential runs cool, quiet, smooth and both rear tires have always locked when tires spin.