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Country Coach Restoration, Repair & Parts Forums => Chassis/Engine Repair => Topic started by: journeyman on March 15, 2021, 06:59:31 am

Title: Gear Lube... Which one for a diff?
Post by: journeyman on March 15, 2021, 06:59:31 am
I am approaching 250,000 miles on my '02 intrigue.
Time to change the gear lube in the differential per Meritor spec.

Meritor recommends GL-5 SAE 75W/90  gear lube.

I am interested in going synthetic. QUESTION: Which one?
I am looking at
Royal Purple MAX Synthetic
AMSOIL Severe Gear Synthetic
Lucal 10048 Synthetic
Motul Gear 300 Synthetic
Millers CRX LS Synthetic

I am looking for recommendations.
Has anyone changed their Diff Fluid to synthetic?
Title: Re: Gear Lube... Which one for a diff?
Post by: journeyman on March 17, 2021, 01:07:11 am
The Meritor axle I have is a 21145
it is a 21,000 Lb. axle, but CC de-rated it to 20k.
(https://i.ibb.co/df9b0vZ/Gear-Lube-Spec-Meritor-21145.jpg) (https://ibb.co/S6TQXgS)

Can anyone help?

Title: Re: Gear Lube... Which one for a diff?
Post by: BlueCoyote on March 19, 2021, 01:21:50 am
Am a believer in synthetic gear lube - do use the correct grade.
IMHO
Avoid purple, Amsoil is good, big believer in Lucas products, Motul is good, never heard of the last one.  Suggest doing it warm, it’s a mess and that diff holds about 4 gallons.
Title: Re: Gear Lube... Which one for a diff?
Post by: journeyman on March 22, 2021, 01:22:55 pm
Am a believer in synthetic gear lube - do use the correct grade.
IMHO
Avoid purple, Amsoil is good, big believer in Lucas products, Motul is good, never heard of the last one.  Suggest doing it warm, it’s a mess and that diff holds about 4 gallons.
You mean USE THE CORRECT GRADE, yes?

Which have you used?
Between Amsoil/Lucas/Motul, is there really THAT much of a difference?

I am wary of shopping by price, but I am wondering if the differences are really measurable in the results.
Title: Re: Gear Lube... Which one for a diff?
Post by: BrianGlenn on March 22, 2021, 05:05:28 pm
I changed mine in my 2007 Allure (meritor RS-21145) to Martin Lubricants SynGard 75W90.  On the recommendation of my chassis guy who rebuilds or changes out "a lot" of drive axles.  Martin Syngard (http://syngardoil.com/).

Brian
Title: Re: Gear Lube... Which one for a diff?
Post by: journeyman on April 17, 2021, 02:02:59 pm
I looked at the SynGuard page:
Martin Syngard Products (http://syngardoil.com/products/) 

And saw the lSynGard™ GL-5 Limited Slip Gear Oil:
Martin Syngard SynGard™ GL-5 Limited Slip Gear Oil (http://syngardoil.com/allproducts/syngard-gl-5-limited-slip-gear-oil/)

I suppose it does not matter if mine is not a LS diff...

Brian, when you changed, did you change from perolium ased to synthetic?
Was there any perceptible change in performance or "feel"?

Title: Re: Gear Lube... Which one for a diff?
Post by: BrianGlenn on April 19, 2021, 03:29:59 pm
No impact to my "Butt dynomonitor or Butt vibration monitor"  I simply think synthetic in a clean environment (like differential) is warranted - better cold weather and hot weather stability in fluid, IMHO.

Brian