I just installed a Limited Slip Diff into my car that has 130K+ miles on it. The diff feels and appears to operate fine except for a shuttering that's felt when starting off in first gear around a turn. Anyway, I'm currently running some cheapo gear oil in it but I plan on installing RedLine MT-90 when I reach a few hundred miles. My question is about friction modifiers. If I use MT-90, will I need a friction modifier? How will I know if I need it and if so how much should I use? Does anyone have any experience with these particular products? Any other tips? TIA

 

I'd like to know, too.

 

Wow, I am in the same spot. I just ask a friend for a quart of Redline 90w and I was going to pick up the LSD additive. I am sure that the mix ratio will be included on the additive. I will let you know when I get it.

 

I installed the MT-90 in my tranmission last night and all I can say is: WOW what a difference! The dino-oil I had in there was pretty new too! (2k miles) Shifts are *much* smoother with the MT-90. I highly recommend this product.

However, after reading up a bit more I have decided NOT to use the MT-90 in my differential. Mazda recommends an API GL-5 oil. The MT-90 is GL-4 rated oil. Instead I am going to try the Redline 75W90 GEAR OIL. This oil exceeds API GL-5 and contains limited-slip friction modifiers. I'll let ya'll know how it is after I install it.

 

Cool. Now off to the performance shop!

 

I've got a friend who has been using Slick 50 gear oil in his diff and tranny for awhlie now, with no problems. I will be trying it out myself once I get mine back on the road.

 

with red line, you do not need the lsd modifier and it says so on the container. I use red line in my manual tranny and the gear oil in the rear...all is fine...I did not notice the big difference that "initab" noticed but I hear it is good stuff,,,,sure cost enough...cjf

 

Just installed the Redline 75W90 GEAR OIL and the chatter outa the rear is now but a memory. nice!

 

Go to any auto parts store and read the back of just about any 75-90 oil, they also say that the additive is not necessary, yet it sure helps (or so I have been told). I my self am also going to be running MT-90 in my tranny, and 75-90 in the rear end once I get to that part of my reassembly . I have never tried Redline in anything, but Im hoping it will be nice in this case. I personally havent decided if I will put in the additive or not. I only mentioned that just about any oil says that you dont need to cause thats what I have read, and if it helps those who also claim they dont need it, wouldnt it make sense that it would help the Redline too? Im still researching the idea though.

~T.J.

 

Redline has two rear gear oils. One with and one without a friction modifier. The one without the friction modifier states that it can be used with work LSD unit to improve LSD clutch grip.

I was unsure of what to do so I called Dave, the tech gut for Redline and asked him.

He said that with a worn LSD I should start with 2.5% friction modify, and if the rear end did not chatter around corners to stick there. If it made noise to add some of the modifier.

So, I mixed I quart of Redline with (premixed at 5%) and one quarter of gear oil with out. I filled the pumpkin and tested it. No chatted, and it seems to work great!