Author Topic: What axle oil to use?  (Read 697 times)

Offline Dunc the Funk

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What axle oil to use?
« on: March 14, 2021, 08:02:42 AM »
I'm just putting the 9" rear end back together & thinking about buying some 85w-140 for it. I was wondering what you more experienced folks use, for example is Lucas mineral Heavy Duty ok or should I step up to, say, some Red Line synthetic?

Offline denverflatheader

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Re: What axle oil to use?
« Reply #1 on: March 14, 2021, 03:07:42 PM »
Iíve used API GL-5 rated in my early Olds, no issues.  However, I did a search and found on the Currie website they state GL-6 for their 9 inch or you void the warranty.  See below from their site:

9-Inch API GL-6 Requirement
Due to the high-offset hypoid design (very high shear) of the 9-inch ring and pinion gears, a severe duty petroleum-based gear oil with API GL-6 specification is mandatory. The use of synthetic or GL-5 specification gear oils will result in premature wear of the gears and excess heat buildup that will damage internal components, voiding the Currie Warranty.

Also from the Currie site:  ALTERNATIVE GEAR OILS THAT ARE PROVEN TO WORK IN 9-INCH REARENDS
Torco - RGO 85w-140
SWEPCO - 203 MolyXP Gear Lube 250w (Racing or extreme application)


And from Mark Williams Enterprises here in Colorado:
4) FILL REAR END ASSEMBLE WITH OIL. FOR DRAG RACING M-W RECOMMENDS TORCO 85-140 MINERAL BASED OIL.

For me, next time I change the diff oil, I'll use an API GL-6, probably the Torco 85w-140 mineral, no synthetic.  Alan

Offline Dunc the Funk

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Re: What axle oil to use?
« Reply #2 on: March 15, 2021, 03:20:50 AM »
Thanks Alan. I did do some searching a few weeks ago & saw sites stating that the Ford 9" was supposed to have GL6 but GL6 was now an obsolete rating so I was pretty confused. I doubt if there's a spate of broken down Ford axles across the world but they may be wearing faster than they should. I will look for some Torco.

Offline THE FRENCHTOWN FLYER

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Re: What axle oil to use?
« Reply #3 on: March 15, 2021, 09:31:17 AM »
I hate the sound of axle gear whine when I'm going thru the lites.

Said nobody ever...

Offline Curly1

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Re: What axle oil to use?
« Reply #4 on: March 15, 2021, 09:49:55 AM »
I think you would be good with any of the good brands, where I have seen people have problems is when they do not use enough oil.