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Discussion Starter · #1 ·
I just changed the oil in my rear differential with Mobil 1 LS and although I read that many of you had to still add a friction additive modifier mine seemed perfect. Now a few days later and although I hear no chattering it seems to be laboring in corners. This may also be my parinoid mind working against me. My question is how hot does a rear differential get after driving. I have a twenty-five mile drive to work where twenty of those are doing 65-70 on the freeway. I can then put my hand on my rear differential but after a few seconds I must remove it because of the heat. Is this normal? I just assumed it never got hot.
Thank-you for any information.
 

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I just changed the oil in my rear differential with Mobil 1 LS and although I read that many of you had to still add a friction additive modifier mine seemed perfect. Now a few days later and although I hear no chattering it seems to be laboring in corners. This may also be my parinoid mind working against me. My question is how hot does a rear differential get after driving. I have a twenty-five mile drive to work where twenty of those are doing 65-70 on the freeway. I can then put my hand on my rear differential but after a few seconds I must remove it because of the heat. Is this normal? I just assumed it never got hot.
Thank-you for any information.
I have a 2004 DC 4 wheel drive and have changed out the oil a couple of times now. I have never felt my differential after driving but will try it today when my girlfriend and I go out to look at plants and let you know. My initial reaction is that the differential is awfully hot. Have you put an infrared thermometer to it?
 

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yes, it gets hot. The friction produces pretty hot temperatures in the case, when I changed my fluid out I ran the truck on a fast trip of about 15 miles on the freeway. When I got back to change the fluid it was warmer than I had expected. I wouldn't worry too much.
 

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Hot is normal. Look how small the diff is and how small its oil capacity is. There are no pumps, filters, or coolers. Now, think of what it has to put up with; 5000+lbs of vehicle on one end and 240hp on the other.

This is one reason I'll always recommend 30k maintenance intervals and full synthetic gear oils, and optional changes to the gear oil weight depending on usage.

I don't always need to use a friction modifier LSD additive with Toyota diffs. Most synth gear oils have a reasonable dose, and many LS diffs are already tired and weak anyway.
 

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Just add some Torco Toyota Friction modifier to your Mobil 1 gear lube that says it has LS addatives in it and i think Mobil was just not putting enough in their LS application. I think a lotta people complained about it not having enough and they added a tad more to fix this issue. It was casuing a serious growling that sounded like it was coming from my front diff but my Master tech drained the rear diff and put dino with modifier back in it which is what OEM called for and all my growling went away in 30 minutes! Not too happy about wasting 3+ liters of Mobil 1 but i will get the Torco specd addative at my 60K interval and will probably do the Mobil 1 again! Most aftermarket quality gear lubes have enough addative to not have issues and i feel Mobil just had a bad run of gear oil that not enough addative was actually installed in their liter bottles or they just did not add enough to start with? Not too sure what normal operating temp would be but that could be figured out a Toby mentioned with a temp probe!
 

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I just got back from looking at landscaping plants with my girlfriend and checked the temperature on my rear differential. About 17 miles of driving in town with top speeds of 50 MPH. I was able to hold my hand flat against the differential comfortably. It was warm but not too hot. I think I have regular Valvoline gear oil in there right now but will change out to Mobile 1 or Amsoil (if I can find it for the right price) at the next fluid change.
 

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^^^ Yeah, if you are paranoid... throw in some friction modifier. Peace of mind is invaluable.
 

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Discussion Starter · #9 ·
Thanks for the quick response guys. Question answered and yes I bought some of the Torco brand as for Toyota. Thanks.
 
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