I've been running LE607 for about 5k miles now and I don't hear any additional noise. Tho, my area rarely gets under 50*F and is more often in the 60ish when cold. When hot, it gets over 100*F.

 

I agree. No one has ever mentioned that before. Placebo effect anyone?

 

Humm. dunno.
I didn't notice any changes in "sound" and I'm usally in San Francisco. where it's been cold lately. I did my change in the cold too. Lemme know.

 

My '02 also sounds the same regardless of whether I use Mobil 1 75W90 or LE 607. There aren't any obvious differences in noise. The reason I say "obvious" is because I usually have my radio on and don't pay any particular attention to what the differential sounds like.

I've had Mobil 1 75W90 in my differential for the last two changes. Left it in there for about a 25k mile interval each time. I've only got maybe 5k miles on the LE 607 so far, but haven't noticed anything different.

 

I'll tell you guys about my experience with differential noise. I decided to change out the differential fluid on my '01 Tacoma 4X4 and dad's '02 Tundra per the maintenance schedule. I used synthetic Mobil 1 90W gear oil and what I noticed immediatley after both changes was that during initial accelerations from a stop especially when the car was turning (e.g. right or left turn after stop sign or light) a unique gear noise was heard almost as if there was no gear oil in the differentials. After some research I found out the the noise was due to a lack of a friction modifier additive that needed to be added. Apparently, GM is the main manufacturer of this stuff for their trucks and it comes in a small black bottle w/ a blue label which I purchased from the counter guy at the Toyota dealership. Immediately after pouring this additive into the differentials of these trucks (one bottle per differential) the noise went away and it sounded perfect again. I never heard anything again. Now, I changed my differential oil out on the "S" after its first 1000 miles per RR's recommendations and I noticed that during mornings when the car wasn't fully "warmed up" yet and I made my usual right out of my driveway, I heard this same noise that I heard with the trucks. So, I'm thinking maybe we need to use this friction modifier additve in conjunction with our differential gear oil. I'm thinking of running the same stuff as I ran in the trucks... Synthetic Mobil 1 90W gear oil w/ GM friction modifier. One significant difference betweent the trucks and the "S", the trucks took about 4 quarts of the differential fluid to fill up plus the friction modifier whereas the S's differential doesn't even take a full quart of differential fluild. Let me know if those of you with experience have any major objections with what I have proposed.

 

Friction modifier is useless in a Torsen type differential. It's only used in clutch type differentials to control the slippage of said clutches and the resulting amount of lockup.

 

It's not just you. The shop that installed my 4.57's used Redline. Even with this brand of oil, I had noise issues from the start. But after 1000 miles on the new gears I switched to 607 and noticed a modest increase in noise; I ignored it cause I'd started to put up with the already increased noise level of just going to 4.57's.

I'd try switching to another brand to see if it's quieter, but I'm hard on my driveline, I've had no issues with 10k miles of 607, and I don't want to risk using something less effective.

 

Using non-FM hypoid gear oil in a clutch pack diff will damage the diff. Using FM in a non-clutch pack Torsen diff does nothing. Go ahead and put some in. It'll just dilute what little fluid we have in the diff and it's your money.