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Discussion Starter #1
How often should it be done? I’ve heard every 30 000 miles. My truck sees basically 85% highway unloaded.
Do I need to pull the cover off, or can I suck the oil out?
 

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Go Packers
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When I change my rear differential gear oil, I pull the cover, and wipe it down clean. Having the cover off gives you the opportunity to inspect inside. Many school's of thought on how often. I change mine close to the 40,000 mile mark. My manual says every 15,000, but that is bit much IMO. Some change longer or shorter, depending on the owner and what's thought best. How often does your manual say?
 

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How often should it be done? I’ve heard every 30 000 miles. My truck sees basically 85% highway unloaded.
Do I need to pull the cover off, or can I suck the oil out?
I wouldn't suggest sucking the oil out, I'm sure it would taste pretty nasty, probably make you sick.:vomit007:

Pulling the cover off is the best way since there is no drain plug, gasket is reusable.

Interval by the manual is 20K I believe on the 2018, but I suggest just doing it when you change the trans fluid/filter at 60K, which is the towing change interval for the 68RFE.
 

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Discussion Starter #4
I wouldn't suggest sucking the oil out, I'm sure it would taste pretty nasty, probably make you sick.:vomit007:

Pulling the cover off is the best way since there is no drain plug, gasket is reusable.

Interval by the manual is 20K I believe on the 2018, but I suggest just doing it when you change the trans fluid/filter at 60K, which is the towing change interval for the 68RFE.
If I add a cover that has a drain plug does that change anything?
 

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Just makes it a whole lot easier to change the oil.
And a whole lot harder to guess if everything inside is still okay.
Plus some of the worst crap will remain in the housing, since the plug can't be at the very bottom.
 

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Discussion Starter #7
Just makes it a whole lot easier to change the oil.
I can only imagine how many times you’ve changed the diff oil on your truck. Never a problem with the gaskets or bolts?
Need to add red locktite every time?
 

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I can only imagine how many times you’ve changed the diff oil on your truck. Never a problem with the gaskets or bolts?
Need to add red locktite every time?
No issues ever, although mines a little more difficult than a stock steel cover as I have an aluminum cover and to get it off you have to take the swaybar mounts loose. But, just to change the oil, I just take the cover loose and let the oil run out, then cinch the bolts back up.

I never use any loctite, and you would especially not want to use red, too hard to get the bolts loose next time.
 

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And a whole lot harder to guess if everything inside is still okay.
Plus some of the worst crap will remain in the housing, since the plug can't be at the very bottom.
I've never found any appreciable crap in mine when changing the oil, and have started to change mine without fully removing the cover.
 

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Just asking.....if your not towing heavy or the rear diff isn’t going into water, why not wait till 100k to change it?
 

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^ FWIW, I've changed alot of oil too, fleets of trucks.
IMO, I'd never use loctite on a diff cover. 1. It's in a corrosive environment area, so over the years, it's likely to get it's own brown loctite (rust). 2. the chances of getting every hole completely clean of lube so the loctite works is alot of work and of diminishing returns in this case. 3. It's not like if a bolt comes loose, it's a catastrophic failure (and through many years and many more vehicles than years, this has never been an issue I recall). Couple bolts loosen up, worst case is a little drip, you see it, tighten them, loctite em if it were to actually vibrate loose again.

In general, from growing up working on cars in the rust belt both personally and as an early career choice, I typically only loctite internal parts (can't get back to em without disassembly of ____) if called for.
On older wore out equipment, sometimes there's that odd bolt that likes to vibrate itself loose and needs glued in.

90% of all nuts and bolts on undercarriages get anti seize or at least some grease on them in anything I work on. Wheel lugs, brake calipers, driveshafts, etc. You tend to learn what rusts together by broken knuckles and rounded bolt heads and snapped bolts and try to prevent those being future occurrences.

And I'd put some good syn gear oil in it and run 50-75k miles before I thought about changing it again.
 

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Just asking.....if your not towing heavy or the rear diff isn’t going into water, why not wait till 100k to change it?
Agree. pickup for example, changed factory fill early on (just because my mindset, anything new or rebuilt gets an early break in oil change) and again at about 100k, oil looked pretty dang good. Just did again recently around 170k on rear axle, still looked good. Did the front that had the same oil since 15k and wished I hadn't wasted the time draining it.
BUT by the same token, just bought an old Chevy Tahoe with only 100k miles on it. Rear diff looked decent, not sure if factory fill or not, vehicle in good shape but evident not impeccably maintained. Front diff was pretty much black. Changed both, just dropped the oil and re-filled. The rear diff on those has a bottom plug and it looked like had to disassemble half the rear suspension to take the diff cover off, lol.
 

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Just asking.....if your not towing heavy or the rear diff isn’t going into water, why not wait till 100k to change it?
Why not? Because all the crap from break-in will still be in there.
But if you make an early change, at say 1,000 to 1,500 miles, then a long time until the next one can be feasible.
 

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Discussion Starter #14
I've never found any appreciable crap in mine when changing the oil, and have started to change mine without fully removing the cover.
So I see a comment like this....then why not just pump the oil out every 30K and leave the bolts and gasket alone?

What’s everyone’s take? Also anyone know where I can find the front breather tube?
 

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@ Tibone
^ Nothing, IMO. Personal preference. There are many axles that you can't take apart reasonably to inspect the gears anyway.
It would be a good excuse to get a cordless impact driver to take the cover off though!
 

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To me it is just so easy to remove the cover, that is what I do!! plus I may be just a little OCD so.....
 
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So I see a comment like this....then why not just pump the oil out every 30K and leave the bolts and gasket alone?

What’s everyone’s take? Also anyone know where I can find the front breather tube?
First off, I don't have a pump, don't plan to buy one just to change diff oil when taking a few bolts loose gets the job done.

Plus, you get more of the old oil out by taking the cover off/loose.

But, it's your truck, you maintain it as you wish, by whatever procedure works for you.
 

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Discussion Starter #19
But, it's your truck, you maintain it as you wish, by whatever procedure works for you.
Sincerely I don’t know what to do here. I’m torn. Part of me says take the cover off, part of me says don’t mess with the gasket and bolts.....really looking for opinions here

Also my truck has 21K miles on it, ca I wait till 30K to change the oil or best to change it now since it’s the same oil the gears broke in on?
 
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