Looking for a bit of advice, rear diff gear oil mistake

As a degreed engineer I respect and appreciate your life's accomplishments. I work side by side with and good friends with a guy who holds a Ph.D. In civil engineering so I have a firm understanding of how your mind works. Basically overthinking and over analyzing the simplest things. yes cavitation is correct but what is cavitation? It's when, in this case, entrained air goes from a low to high pressure atmosphere the air bubble grenades causing metal erosion and burnt oil. Yes burnt! Try temps around 1500F. Implosion on the vacuum side of the lubricated surface and expansion/ collapse as pressure zone changes. These are instances of both gaseous and vaporous cavitation.
To answer another question yes additives are put in oils to help disburse entrained air but it only helps- doesn't prevent. Generally speaking gear oils are under extreme pressure that's why a lot of gear oils say EP as they have additives to help prevent degradation and shear under these conditions. my apologies for just trying to generalize something so simple. All of this still means "bad stuff happens"

 

I'd chalk it up to being a coincidence as I bet it would have happened if you left the previous oil in there or had another shop perform the job. Just about any modern day gear oil out there is going to cover the basic needs of a differential.

I'd go for finding a good used one or having your current one rebuilt rather then buy new.

 

$2400.....WOW!!!!

ECGS for a ready to go 3rd and 2 hours of time with basic hand tools....

ALso, like others have said, check those rear axle bearings....you'll probably find the roar there.

 

Need more details. Did your invoice specify the type of oil used?

What the hell is a flush for the rear diff? There's a drain plug at the bottom of the diff housing and a fill plug about halfway up. By the book you just drain out the old oil and fill it up with new oil. Did the shop run some snake-oil "treatment/conditioner" thru the diff?

Simply using 75W140 does no harm. It's the same viscosity range as 75W90 when cold, but resists thermal breakdown better when hot. Been running 75W140 myself since 2014. It's considered a better (and more expensive) oil than 75W90.

 

Oooh fancy. Must have been hungover for your fluid dynamics class because wiki agrees with @maxtherat
https://en.wikipedia.org/wiki/Cavitation

Here i'll save you the click...
Cavitation is the formation of vapour cavities in a liquid – i.e. small liquid-free zones ("bubbles" or "voids") – that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities where the pressure is relatively low. When subjected to higher pressure, the voids IMPLODE and can generate an intense shock wave.

 

Hmmm ... You have a friend with a PhD in civil engineering and now you know how my mind works??? You don't know shit about ME, we have never met and your qualifications for this analysis are, you have a friend who's a psychologist?? I just simply asked for an explanation of your oil theory. Thanks.

Correct, max stated that the voids "explode" until restating in post #21 No hangover, he misstated in post #6

 

I'll say this, max cannot explain things well, at all. but he's qualifed

I know, boy do I know. My Qualifications ? I know someone who knows how to install ebay bumpers

 

As far as the oil theory goes: look into ICML they know a thing or two about this kind of stuff
As far as you being an engineer I meant no offense other than all of the ones I know, including my father, tend to be very analytical people. I'm sorry you had to use this forum as a venue to start a fight with people that are just there to offer their support and opinions.
And for the record you are the one who had to make mention that you are a "degreed engineer"

 

Actually it does happen. Bubbles do pop under compression, and that can erode gear surfaces. Just like underwater cavitation on a boat prop can eat away at the prop. But obviously that is not the MAIN problem here. Air bubbles have a lousy coefficient of friction since they displace oil, and you are effectively running the surface dry wherever a bubble hits.

 

I feel for you OP, and I'm sure you don't want to see this in your thread.

I'M SURE THERE ARE MORE ENGINEERS HERE BUT DON'T WANT TO SHOW UP!!!

 

Implode, explode, tomatoe, tomato ...lets not get bent out of shape here. Important part is air is where oil should be, doesn't take a degreed rocket appliance to figure out that's bad.

As for the OP, unless you run the thicker oil in the dead of winter, I can't imagine it would do major harm and if so it would take awhile to manifest.

 

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Be honest, you googled that shit and threw it up here as your own!

 

I am gonna engineer myself a sandwich tonight, and report back tomorrow !

 

When I changed my oil I was told not to mix the synthetic with non synthetic gear oil, something about it coagulating. Idk if that helps at all.

 

No actually I did not. Unlike others here will not mention any names I actually have workplace experience and certification in this particular area. Do you actually think I pulled ICML out of my ass? I just didn't think there was any relevance in having to justify my opinion when someone asks for it. Just like I never asked mr engineer for his credentials.

 

What? I never said I was an engineer, was just pointing out what I was told when I changed my own gear oil. It's been over 30k miles since I did mine so I can't remember specifics. I was just thinking if the oil does in fact coagulate when mixed like the person said it could cause problems. Also, I filled mine up to the tippy top and some and it didn't cause any problems for me.

 

Not you. I was referring to the clown who started stirring the pot early on in this thread.

 

For some reason my comment went to you and not @TacomaMike37. Sorry!

 

Oh, I see.

Is what I was referring to a thing? Would that be the "bubble" thing you guys were referring to? I remember it was like 3 different washers as well, kinda annoying to change actually.

 

Cavitation is the formation of vapour cavities in a liquid – i.e. small liquid-free zones ("bubbles" or "voids") – that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes ofpressure that cause the formation of cavities where the pressure is relatively low. When subjected to higher pressure, the voids IMPLODE and can generate an intense shock wave.

had that ^ happen after eating a burrito the other day Op... do you do much towing with your 06?