I'm sorry, but my point is that these do not answer the question. As I understand it, first, it is not really a Torsen unit which is a purely gear driven mechanical LS Diff. I have an actual Torsen unit in my C4 corvette so I know how they work. This is a upgrade from the standard clutch pack with the Bellville washers. My actual Torsen unit does not require LS additive because there are no clutches.

Second the fact that it is a tochigi Fuji unit does not define if it is a purely gear type unit or has a clutch type engagement because I am not familiar with this unit or company, hence the nature of my original question.

Third, there are Torque sensing units that are gear based and others that have clutches that engage based upon hydraulic pressure. The latter of these sometimes requires an additive similar to my LS2 GTO which has a cone system made by ford of Australia. It requires a ford type additive. The LS additive typical of RP, Mobil, and others do not meet the F requirement.

I am not trying to be difficult, but I have read in several places on the forum that it is a gear unit and does not require LS additive and other places just say that it requires additive just because it is an LS (but we know there are LS's out there of gear type that do not require additive).

So my question remains; Is the tochigi Fuji unit purely gear driven and so it does not need an additive or does it have clutches of some type that engage and then if so, what is the specific additive requirement?

Gear type....just use good Synthetic gear lube that meets the specs and go from there :)

Thanks for the clarification. I wanted to use one without additive and so that will work.

It's actually not a Torsen nor anything like one. We all assumed that long ago. So the entire thread is fubar. It's a cone-clutch type LSD.

So does it require LS additive of a specific type or does this cone clutch system not require LS additive? Sorry for the questions, but I have been reading for hours and can't seem to get a definitive answer.

Standard gear oils have some included already. Only a gear oil like Redline 'NS' variations don't have it. You will be fine with regular gear oil as dannobre mentioned.

So just to be clear is LS additive required for the cone clutch or is non required?

Anyone know if the stock diff is 1-way, 1.5-way or 2-way? I'm trying to get a better understanding of off vs on throttle traction.

Effectively it is a 1-way diff. It only is active when power is applied and a difference in wheel speed. Otherwise it is open diff

https://cimg2.ibsrv.net/gimg/www.rx8...c50e1ddd51.jpg
https://cimg0.ibsrv.net/gimg/www.rx8...9482e0d023.jpg
https://cimg9.ibsrv.net/gimg/www.rx8...0ba0c984fd.jpg
Will an open diff from an auto fit in a manual pumpking? Are both the M/T LSD and A/T open diff the same sizes? Will cv axles fit ? Are all years interchangeable? It appears so.. Best thing for a constant 100% lock on both wheels drift or drag or whatever reason would be to get an open diff from an auto and weld it and put it in your manual rear end and just swap it out with the LSD unit.. Or spend like a grand and buy a spool from Australia for the ultimate weight reduction in rotating mass...

Hey

Terry
 

Re Rx8 DIFFS- I have pulled a fair few auto’s diff’s apart for the Mazda RX8 In Australia, looking for non-damage thrust plates to put in my track car which have a controlled diff ( can’t be changed) & they have all been lsd’s and they have all been damaged! Mainly the four tabs are completely broken off or cracked & are about to break. The funny thing is they still work when the tabs are broken so deceptively hard to determine if they’re broken. big job to have a look & a rear wheel alignment is necessary afterwards Terry lewis Rotary Motion