Is This My Imagination or What?

[CharBaby]

I always use a gear oil with the LS additive already in it whether I need it or not.

 

[CharBaby]

I always use a gear oil with the LS additive already in it whether I need it or not.

Let me rephrase this.^^^
I use the proper gear lube & grade/weight and GL# for the application...with the LS additive.

 

[diyjake]

I had this shudder on take off at 15 mph in my 2005 LS430. Not every time. Very Slight.
Gone at 20 mph. I posed the question here and obviously, it couldn't really be answered in a forum.

Last night I decided, what the heck, let's drain and try a different gear oil. No biggy.
See if a different brand of gear oil would alleviate this shudder.

I changed it out and drove to the dumpsters. About a 10 mile round trip. The shudder
is gone. I stopped and started probably 30 times. No shudder.

Full disclosure, the gear oil that was shuddering was a 75W-110 and I replaced it with
75W-90. Two well known and highly respected name brands.

I ain't gonna tell you what I was using or what I substituted. Not here to bash and get
panties all in wads.

My question is, could that slight shudder have been caused by my differential not liking
a particular brand?

Please share what brand you used before and after. After all a lot of us are here to learn what is good and not good and peoples personal experiences like yours might help the next guy when he goes to change his gear oil.

 

[Greasymechtech]

If you have a limited slip diff, not all gear oil with LS additive are dosed high enough. Brands used makes no difference. Installer error!

If my diff doesn't need LS additive, I always use a gear oil WITHOUT LS additive.... like Motul/Redline/Torco or any of the OTR trucker GL5's

So, if you get any diff chatter/shudder, you incrementally keep adding LS additive until it goes away. And, any time you change the gear oil with an LS diff, you need to do some parking lot figure 8's to work the new fluid/additives into the LS clutches. Common sense that has been lost to the masses of mechanics!

This isn't about grade/brand or even grade of gear oil. I'd wager LS additive dosage or worn component harmonic.

If 300k+ mile Lexus doesn't have a functioning LS diff, then the thicker fluid could of changed a vibration/harmonic from 'other' worn out parts in the driveline.

Limited Slip Supplement - Lubegard

www.lubegard.com

Limited-Slip Friction Modifier

Compatible with both petroleum and synthetic gear oils

www.redlineoil.com

Slip Lock

Shop Slip Lock at AMSOIL. Find premium synthetic oil, filters and more online. Fast, free shipping available.

www.amsoil.com

Torco Limited Slip Additives

Torco Limited Slip Additives type F are formulated for use in limited-slip and posi-traction differentials to reduce hypoid gear noise and chatter. LSD additive.

torcousa.com

At least one brand provides some common sense instructions:
AMSOIL SEVERE GEAR is compatible with most limited-slip differentials. For applications that require additional limited-slip friction modifier, add AMSOIL Slip Lock®.

 

[Snagglefoot]

I would re-check your fluid level for the next while, say at oil change intervals. A low fluid level will cause noise. If you find the fluid low, pull off your wheels and have a look for leakage at the axle seal.