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I recently bought a Certified Pre Owned 2016 GX with approx 45,000 miles.
In September, I changed all the fluids (Front/Rear Diffs, Transfer Case, and ATF).and thought that the rear end noise would be reduced with new fluid.
NO CHANGES.
Took the car to the dealer and without telling me, they DRAINED my rear diff fluid and put in a glass jar, and refilled with their bulk 75w-90. I was very upset.
Came back a few hours later with two oil analysis kits and sampled their virgin gear lube along with my suspected gear lube that they drained.
What is very concerning, the Rear Diff fluid that they drained, was BLACK after 833 miles.
Sending the used sample along with the dealers bulk sample for oil analysis.
I'm using Amsoil Severe Gear.
This noise was not present in my wife's 2018 and our 2019.
I have searched this model forum and have read other members issues.
The noise is still present with the dealer gear lube installed also.
Have a case opened with the dealer and going to return in 500 miles.
How did the old oil look that came out when you replaced it with the Amsoil? Being the skeptic, I'd suspect that the dealer just took old oil from a large container of used oil from other oil changes. Maybe they didn't even change it at all, just handed you some old oil. Since you have to go back in 500 miles, drain some right before your visit to look at it yourself and to get your own sample if you want to do another oil analysis. This way when the dealer replaces it again you can compare your sample to their latest sample. OTOH, since you have a rear end noise, perhaps there is something wrong with the diff which would make the oil black in less than a 1K miles. Can you tell us more about the rear diff noise?
I used the mystery oil that they showed me and sent a sample of it to the lab for analysis along with the virgin gear oil that they use and put in the rear diff for analysis.
The gear lube was black and much darker than the stuff I drained about before. The whine/howl was present before the diff fluid change.
The howl is only present when you let off the accelerator (really only noticeable at 60-65 MPH) and then goes away the second you press on the accelerator. The issue is not present while on cruise control.
Are you positive the whine is from the rear diff? I have the same whine just as you described but it’s coming from the front though. I searched the archives and read numerous threads on this issue. Seems to be more of an annoyance than anything serious. Last month along with my 60k mile service, I replaced front and rear diff fluids with Amsoil Severe Gear as well. The whine is still there. Other than the noise, no driveability issues. BTW, no way in hell your recently replaced fluids came out black in only a few hundred miles. My previous experiences with diff fluids after 50k miles they were still amber, not black. They probably gave you a sample from their collection/recycle tank.
I'm certain it's from the front along with the dealer.
The sample they gave me is off to the lab. Amsoil will be able to tell if it's severe gear or not when the results come back.
Here is a picture from last night with the used Gear Lube (833 miles), Virgin Severe Gear, and Virgin dealer bulk.
Wow, that is very dark. Since they changed the oil without your authorization, your request for a sample came after it was changed, meaning it was probably already mixed with other oils.
It was wise of you to send the samples in to Amsoil for them to analyze them, we look forward to the report you get back.
I also read your other thread; GX Transfer Case Lube about the dealer using generic 75w-90w synthetic transfer case oil instead of the expensive 75w Toyota TC oil. Sadly, I think this is the norm at many dealerships, they just use the cheapest to save money.
Search 'Synthetic Oil Change Scam' on youtube, makes one never trust any shop, unless you bring in your own oil and they let you watch them carefully as they change it.
This is from the Amsoil site on the Severe Gear Product info....
""AMSOIL SEVERE GEAR EP Gear Lube excels in hot and cold temperature extremes. By design, it resists breakdown from high heat, preventing acids and carbon/varnish formation. Its wax-free construction also improves cold-flow properties, improving fuel economy and cold-weather shifting.""
Does anyone feel that the short run on Severe Gear IS cleaning the differential of "CARBON" formation ?? Amsoil told me that one reason for SG to darken that quickly would be oxidation due to excessive heat. I don't know what the factory fill would be for the differentials, but know the stuff I drained out of the diffs was just as darker or darker than what I'm showing in the picture.
Just trying to educate myself on this.
Appreciate all the comments on this potential issue !!!!
I had to look at my past service post (Post# 26) I had around 36K miles when I changed mine and fluid was still pretty clean and magnets were as follows:
• Rear drain magnet seemed to only have light coating of material attached to it. • Front magnet was fairly substantial in coating
09-24-19, 05:29 PM
