2008 4R 4x4 rear diff hum

[KB084RUNNER]

I have a 2008 4Runner 4x4 with about 3500 miles and I get a slight rear diff hum on the highway at 60mph. Anybody else get this issue? The dealer claims they can't hear it but my 10 year old daughter can.

 

[lechec66]

Same here. It has gotten quieter the more miles I put on, or I am just getting used to it. Didn't ask the dealer about it, was more worried about my loose driver's seat.

 

[KB084RUNNER]

I was thinking about dumping the factory fill 80w90 diff oil and trying some Amsoil 80w90 or Mobil1 75w90 synthetic. How many miles do you have on your 4R?

 

[lechec66]

I was thinking about dumping the factory fill 80w90 diff oil and trying some Amsoil 80w90 or Mobil1 75w90 synthetic. How many miles do you have on your 4R?

Only 5k. Some others on here have swapped fluids and it has made an improvement.

 

[KB084RUNNER]

Do you know what gear oil they used?

 

[CJ3Flyr]

Do you know what gear oil they used?

Many use Mobil1, Amsoil, Redline or Royal Purple, basically a premium synthetic. I like the idea of doing the first diff and t-case change early (5-10k) just to get the 'break-in' shavings and junk out. Then I'm happy to run a good synthetic a more normal interval. If you follow Toyota's suggestion for towing they'll have you do it every 15k. If you don't tow they say never :wtf: (Remember the Toyota #'s are based on conventional oil vs. synthetic.)




I think a good synthetic and 45-90k, depending on use, is smart.


:cheers:

 

[KB084RUNNER]

Many use Mobil1, Amsoil, Redline or Royal Purple, basically a premium synthetic. I like the idea of doing the first diff and t-case change early (5-10k) just to get the 'break-in' shavings and junk out. Then I'm happy to run a good synthetic a more normal interval. If you follow Toyota's suggestion for towing they'll have you do it every 15k. If you don't tow they say never :wtf: (Remember the Toyota #'s are based on conventional oil vs. synthetic.)




I think a good synthetic and 45-90k, depending on use, is smart.


:cheers:

So if they are using Mobil1 then they are using a 75w90 in the rear diff. I was just wondering since the rear diff spec is 80w90 if there were any noise issues using 75w90 synthetic. My only towing will be a small uhaul trailer taking my daughter to college which is a 400 mile trip total once a year.

 

[CJ3Flyr]

So if they are using Mobil1 then they are using a 75w90 in the rear diff. I was just wondering since the rear diff spec is 80w90 if there were any noise issues using 75w90 synthetic. My only towing will be a small uhaul trailer taking my daughter to college which is a 400 mile trip total once a year.

No issues. The way the oil ratings ratings work 75w-90 ends up being better. I've driven a couple T4R's and many other truck based SUV's. There's usually a bit a hum. I use Amsoil for axles and t-case. I have a touch of hum.

Clean, fresh synthetic will probably reduce the noise, it did for me. It will probably not eliminate it.

:cheers:

 

[KB084RUNNER]

Thanks everybody...my local auto parts guy is an Amsoil dealer so I checked their website and they do make a full synthetic 80w90 so I'll be getting that for sure.