Front and rear gear oil

[4WD]

Have driven 4WD trucks and SUV for decades and have always changed F/R gear oil around 30k. That is probably too conservative for modern lubes but it might take 3-4 years to put that on my least used but most abused vehicle.
(And I suffered an expensive gear lube failure)

1) How many feel both front and rear need to be changed together if not AWD (selective 4WD)?
2) How many for use of the same lube F/R vs something boutique in the rear only?

 

[Shannow]

My Nissan Navara had hubs to lock the front diff in...ad 75W90 spec for the front, 80W140 for the back.

I used mineral in the front, synth in the back...Once used 75W140 RP, and it came out black and "globby"

 

[Colt45ws]

ITs not really for a first change...in fact I believe 10 or 15k is a good point for a first change. Remove the break-in wear.
After that, 50k or more depending on application.
Your questions are very vehicle dependant. If you have a Full time 4WD or AWD where both are always spinning, then changing them together makes sense.
If you have a 4WD pickup that mechanically disconnects the front drive shaft and unlocks the hubs, then the front diff is not spinning the greatest majority of the time.
In that case, if you changed every 50k or something with the rear, then you'd be throwing out almost 'new' oil.
I think the other question has the same answer...since so few miles are getting put on the front, and what is, is likely at relatively slow speed then putting reasonable quality 80W90 in the front is probably just fine.
In the back, I think a high quality synth is a good default.

 

[chrisri]

I'm using in my Nissan Terrano R20 mineral 80w90 GL5 in front diff, transfer box and gearbox(yellow metal friendly). Plan to change it every 30k km. Probably to conservative but the truck is off road/family trip vehicle and I don't mind as I plan to keep it long time.

For rear I use Castrol 90w140 GL5 LSD fluid as required. 30k interval is what I plan.

 

[dlundblad]

Originally Posted By: 4WD
Have driven 4WD trucks and SUV for decades and have always changed F/R gear oil around 30k. That is probably too conservative for modern lubes but it might take 3-4 years to put that on my least used but most abused vehicle.
(And I suffered an expensive gear lube failure)

1) How many feel both front and rear need to be changed together if not AWD (selective 4WD)?
2) How many for use of the same lube F/R vs something boutique in the rear only?


As you know, the rear is worked harder than the front, but how much more? Do we have a real number that includes 4WD and towing usage? With my setups at least, the gears are always turning. There may be a little less heat or strain on the diff, but they're still getting some amount of wear nonetheless. Do it together and be done with it.

I try to use the same in both just to make things easier (ie no various quarts of partially used gear oil), but it depends on what I have on hand too.

 

[4WD]

Originally Posted By: dlundblad
Originally Posted By: 4WD
Have driven 4WD trucks and SUV for decades and have always changed F/R gear oil around 30k. That is probably too conservative for modern lubes but it might take 3-4 years to put that on my least used but most abused vehicle.
(And I suffered an expensive gear lube failure)

1) How many feel both front and rear need to be changed together if not AWD (selective 4WD)?
2) How many for use of the same lube F/R vs something boutique in the rear only?


As you know, the rear is worked harder than the front, but how much more? Do we have a real number that includes 4WD and towing usage? With my setups at least, the gears are always turning. There may be a little less heat or strain on the diff, but they're still getting some amount of wear nonetheless. Do it together and be done with it.

I try to use the same in both just to make things easier (ie no various quarts of partially used gear oil), but it depends on what I have on hand too.



Agree I can’t measure the difference … but have a locker in the rear and open differential in the front …
2WD mode is just that. There are a number of things turning in the front … somewhat passive I suspect …
Probably do both on both … Delvac 1 in the rear and M1 in the front … cheaper than Amsoil at least … I’ll get some Amsoil synchromesh for transfer case …

 

[JHZR2]

Absolutely change the front.

Ive always noted signs of moisture in my 4wd front diff, likely due to the lack of time under load.

 

[Rand]

Originally Posted By: dlundblad


As you know, the rear is worked harder than the front



That too is vehicle dependent.. AWD was mentioned in his question.

Some are RWD/AWD system such as the Jeep grand cherokee.. definitely more "work" from the rear differential.

FWD/AWD based systems such as CR-V, Jeep Cherokee etc is the opposite.

 

[benjy]

in my 2011 Nissan SV 4.0 with the Nissan-Dana rear i used RedLine REAL synthetic 75-90 as noted on the literature i got with the Spicer alum cover i installed aka titan cover, same lube in the front. only 30 thou but older a lived in Massachusetts prior. checking the Dana specs a 75-90 real synthetic recommended unless its run very hard or towing. i just drive my truck + only haul very little. the OE Nissan lube is a cheaper to make but costly being OE, mineral lube where the Redline is Ester based + one of if not the best IMO

 

[barkingspider]

In my GMC, I have syn 75w90 in the rear and I will change prolly after 60-70k miles. I have 80w90 in the front and will change it once a year (approx 20k miles) as it’s cheap and easy..

In my AWD Escalade, I have syn 75w90 in both. Replaced at 165k miles, I have almost 190k now, prolly won’t change ever again unless I keep it passed 250k miles

 

[4WD]

Not AWD and selective 4WD was mentioned in OP

 

[dubber09]

Changing F/R diff oil on my Sportage every 30K km, easy to do, not expensive, gears are clean, oiled and happy...

 

[ZebRuaj]

Like others said, vehicle dependent.

07 V6 4Runner with selective 4WD: 75w90 in F/R + transfer case. Mentally, I've accepted 50k gear oil changes since it's a DD on pavement. I change it all at the same time since I'm already under the rig. The rear diff gear certainly gets abused more since its rarely engaged in 4 Hi.