Rear axle temps

[Oletimer]

So i decided to use a thermal temperature gun on my rear diff. It was warmer than i thought it should be, 160.
So i changed out dealer oil for 75/140 royal purple and the next time i ran the same 60 mile trip with same outside temps , rear diff was lower at 152.
So for kicks i changed it again to 75/140 lucas dino oil.
Ran same trip again a few days later 6 degrees warmer outside and rear diff was 142.
Is synthetic really better ?

Sponsored

 

[rustyshakelford]

@CarbonSteel I think I have met your long lost brother!

Darrell, CS has probes in his diffs to record temps. He’s done a lot of work on this project and I’m sure can help you out with his research

Brett

 

[pablo_max3045]

Is synthetic really better ?

I guess it depends on what you mean with better. But generally, yeah.. unless the application was designed to use mineral oil, synthetics (good quality) oils are better.
They have a higher natural viscosity index and also "stick" to the metal a lot better than mineral oil.

From the "oil guy"
Eaton conducted tests on oil/component durability during the late 1980s early 1990s

Their intent was to maximize seal and gear life and to allow the maximum OCI possible for their Heavy Truck gearboxes and diffs when using 75w-90 and SAE50 gear oils

They found;
a) components should not be operated at consistent temperatures above 250F
b) Intermittent operations to 300F do not harm the components or oils (synthetics)
c) Oils with a sulphur/phosphorus additive package activate rapidly above 230F.(BAD)
d) A poor additive package in a synthetic lubricant may not be as good as a good (thermally stable) additive package in a mineral oil
synthetic gear oils (75w-90 and SAE50) usually reduce operating temps by from 10-20C

 

[Oletimer]

@CarbonSteel I think I have met your long lost brother!

Darrell, CS has probes in his diffs to record temps. He’s done a lot of work on this project and I’m sure can help you out with his research

Brett

I would be interested to know what rear diff temp is after a good run of at least 50 miles in about 70 degree weather. Thanks

 

[Oletimer]

I guess it depends on what you mean with better. But generally, yeah.. unless the application was designed to use mineral oil, synthetics (good quality) oils are better.
They have a higher natural viscosity index and also "stick" to the metal a lot better than mineral oil.

From the "oil guy"
Eaton conducted tests on oil/component durability during the late 1980s early 1990s

Their intent was to maximize seal and gear life and to allow the maximum OCI possible for their Heavy Truck gearboxes and diffs when using 75w-90 and SAE50 gear oils

They found;
a) components should not be operated at consistent temperatures above 250F
b) Intermittent operations to 300F do not harm the components or oils (synthetics)
c) Oils with a sulphur/phosphorus additive package activate rapidly above 230F.(BAD)
d) A poor additive package in a synthetic lubricant may not be as good as a good (thermally stable) additive package in a mineral oil
synthetic gear oils (75w-90 and SAE50) usually reduce operating temps by from 10-20C

I know synthetics are better according to just about every one, it just really surprised me when temps dropped after putting lucas oil in.

Im going to put a few miles on just because , see what it looks like after a few thousand miles.

Thanks

 

[CarbonSteel]

I would be interested to know what rear diff temp is after a good run of at least 50 miles in about 70 degree weather. Thanks

Still in progress; I am waiting on my Ram mount (https://www.rammount.com/part/RAM-DT-204-TRACK-A12U) to arrive to mount the gauges.

 

[JIMBOX]

Sometimes/someways modern tech doesn't improve our systems enough to write about, but

With all the latest tests and evaluations--SYNTHETIC OILS-ROYAL PURPLE/VALVOLINE/MOBILE-ETC will give the greatest ops in your DIFFS !

When I changed my '08 JKUR diff gears to YUKON 5.38s several times , my front/rear diff temps ran over 300 deg-and I used VALVOLINE 75W-140 syn---I never had any troubles and still use it to this day !-

W.E.

JIMBO

 

[Oletimer]

Sometimes/someways modern tech doesn't improve our systems enough to write about, but

With all the latest tests and evaluations--SYNTHETIC OILS-ROYAL PURPLE/VALVOLINE/MOBILE-ETC will give the greatest ops in your DIFFS !

When I changed my '08 JKUR diff gears to YUKON 5.38s several times , my front/rear diff temps ran over 300 deg-and I used VALVOLINE 75W-140 syn---I never had any troubles and still use it to this day !-

W.E.

JIMBO

Thanks, ive never checked reqr diff temp before on a jeep. I was just wondering because of lack of capacity if it maybe caused hi temps. I guess 150 ish is fine.
But i have to ask, why do you think your temps were so high ?

 

[Oletimer]

Still in progress; I am waiting on my Ram mount (https://www.rammount.com/part/RAM-DT-204-TRACK-A12U) to arrive to mount the gauges.

I would love to know your temps when you get it all rigged up.
Thanks

 

[CarbonSteel]

I would love to know your temps when you get it all rigged up.
Thanks

I will be sure to update you and the thread. I am running Amsoil Severe Gear 75W-110 in the front axle (M210) and 75W-140 in the rear axle (M220) with OEM covers on both.

 

[JIMBOX]

Thanks, ive never checked reqr diff temp before on a jeep. I was just wondering because of lack of capacity if it maybe caused hi temps. I guess 150 ish is fine.
But i have to ask, why do you think your temps were so high ?

My diff/ temps were high because the NEW YUKON 5.38 GEARS were breaking in--(FRICTION)

The normal op temp after 1000 miles was about 100 degrees !, with obvious changes while OFF-ROAD !

Good luck

JIMBO

 

[CarbonSteel]

Sometimes/someways modern tech doesn't improve our systems enough to write about, but

With all the latest tests and evaluations--SYNTHETIC OILS-ROYAL PURPLE/VALVOLINE/MOBILE-ETC will give the greatest ops in your DIFFS !

When I changed my '08 JKUR diff gears to YUKON 5.38s several times , my front/rear diff temps ran over 300 deg-and I used VALVOLINE 75W-140 syn---I never had any troubles and still use it to this day !-

W.E.

JIMBO

If your axle temps were constantly at 300°F and above (meaning this was normal and continuous operation), there was something happening inside the axle that should not have been. I towed heavy in high heat and in the mountains with a 2010 FX4 F-150 and a 2015 F-250 Powerstroke and rarely saw temperatures above 230°F for any length of time. Normal operation when towing was in the 190--220°F range (usually below 200°F). I hope to have my gauges installed soon so that I can see how the Dana axles fare in my Rubicon.

 

[Oletimer]

My diff/ temps were high because the NEW YUKON 5.38 GEARS were breaking in--(FRICTION)

The normal op temp after 1000 miles was about 100 degrees !, with obvious changes while OFF-ROAD !

Good luck

JIMBO

Thanks

 

[JIMBOX]

If your axle temps were constantly at 300°F and above (meaning this was normal and continuous operation), there was something happening inside the axle that should not have been. I towed heavy in high heat and in the mountains with a 2010 FX4 F-150 and a 2015 F-250 Powerstroke and rarely saw temperatures above 230°F for any length of time. Normal operation when towing was in the 190--220°F range (usually below 200°F). I hope to have my gauges installed soon so that I can see how the Dana axles fare in my Rubicon.

You might try READING MY POST, BEFORE YOUR WILD JUDGEMENT !

W.E.

JIMBO

 

[CarbonSteel]

You might try READING MY POST, BEFORE YOUR WILD JUDGEMENT !

W.E.

JIMBO

We crossed posted (meaning you posted your explanation while I was typing) and nothing I said was "wild judgement". If you have constant temperatures above 300F, then something is wrong--gears breaking in or not.

Sponsored