Do I need friction modifier or not

Hi. I have a 2003 Tundra with an LSD rear axle. I called the local Toyota Dealer and they recommended a 80W-90, they did not say anything about a friction modifier additive. I went and bought Valvoline High Performance SAE 80W-90 for LSD. My question is this, do I need to add the friction modifier additive along with, or just the oil. Thanks

 

I have the 2004 with the same rear end and have always added it. No issues to date. However, I have heard that not adding will lead to rear end chatter as GT described

 

I had an 05 with LSD and I always changed it with royal purple and never added the friction modifier. I had no noise coming from the rear end. When I was doing my research before people were saying it all depends on which brand you use. I was contemplating between Royal Purple and Mobile 1. I ended up using Royal purple because I didn't have to add the friction modifier.

 

Thanks for all the responses. I saw through research that many people said to stay away from using Synthetic Gear Lube in the 00-06 Tundras with LSD, am I wrong in thinking this? That is why I went with the Valvoline High Performance " Made for LSD ". Does the " Made for LSD " mean it already has friction modifiers in it?

 

I usually buy fluids like that, that aren't changed too often at the dealer parts counter, that way you know you'll get the correct juice for your Toyota, Honda, Hyundai, etc. I just did that for my car's manual box. A bit more money, but at least you know it will be correct for the particular application. Chunk.

 

So I performed a drain and fill on my rear diff. What came out looked really good and the drain plug had next to nothing on it, so this was definitely a preventative measure than anything. The friction modifier I used required one bottle per 2qrts, so I added 1.5 bottles. Took her out for a test drive and started nice and slow. I did hear a groan at first but it went away the more I drove, I figured the friction modifier had to mix up with the gear oil. Went to a parking lot and did about ten figure 8's and did not hear any groans or clutch chatter. Took her to work today ( 8 mile drive ) and everything was smooth and no noises or chatter.