Royal Purple diff gear oil
Thread Starter
Le Mans Master
Joined: Jan 2001
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From: Maryville TN
St. Jude Donor '06-13,'16-'17, '19
Royal Purple diff gear oil
I just drained my diff and refilled it with 2 quarts of Royal Purple gear lube with friction additive.
A club member said that was a major mistake! He said that I should have used GMs gear lube and a bottle of their limited slip additive.
Have I screwed up?
Tom
A club member said that was a major mistake! He said that I should have used GMs gear lube and a bottle of their limited slip additive.
Have I screwed up?
Tom
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Yes , since the lube you used is too slick, will lower the break away value of the LDS clutchs that should be at 100lbs if you use the correct lube (do not add more limited slip additive, since it already in the lube),
to something way lower, and will end up with peg leg burn outs. Also, since the clutch packs are not locking up correctly to 100ftlbs, just means that you are burning out the clutch packs a lot faster since they are slipping more instead.
Last I check, someone else to rebuild a diff to replace the clutch packs is a few thousands, so would eat the cost of the RP, and get the correct fluid in play now. Also, once you do have the correct fluid in play, large parking lot to do tight slow figure 8's both ways, to flush the RP out of the discs, and get the correct fluid back in them.
Same with using the correct trans fluid, since the synchro's have clutch disc discs as well, and too slick of a fluid will end up with them not working correctly and burning them up quickly too.
Last edited by Dano523; May 30, 2022 at 07:43 PM.
Melting Slicks
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From: home
Sorry to disagree, but synthetic gear oil will not cause any clutch problems in the diff. Actually the additive causes the clutches to slip. Slip=heat=wear=more slip= more wear. That is why the chatter when turning goes away when the additive is used, the clutch plates are sliding easier on themselves. Our preference is mobil 1 75w-90 delvac without the additive. For manual transmissions, we use pennzoil syncromesh
Thread Starter
Le Mans Master
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From: Maryville TN
St. Jude Donor '06-13,'16-'17, '19
Great write up Dano! But I was under the impression that the Dexron was for 2008 and above. The 05-07 used the synthetic gear lube from the factory.
From the 2006 manual:"SAE 75W-90 Synthetic Axle Lubricant (GM Part No. U.S. 12378261, in Canada 10953455) meeting GM Specification 9986115. With a complete drain and refill add 4 ounces (118 ml) of Limited-Slip Axle Lubricant Additiv(GM Part No. U.S. 10523Canada 992694) where required."
The reason I selected Royal Purple was because it was a synthetic and had the limited slip additive already added.
Tom
From the 2006 manual:"SAE 75W-90 Synthetic Axle Lubricant (GM Part No. U.S. 12378261, in Canada 10953455) meeting GM Specification 9986115. With a complete drain and refill add 4 ounces (118 ml) of Limited-Slip Axle Lubricant Additiv(GM Part No. U.S. 10523Canada 992694) where required."
The reason I selected Royal Purple was because it was a synthetic and had the limited slip additive already added.
Tom
Last edited by TCW; Jun 1, 2022 at 03:38 PM.
Le Mans Master
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From: Charlotte NC
St. Jude Donor '14-'15
I remember back when my rear car making a terrible noise from the back end, Loud clunking. Posting and reading looked like I needed some work done. Someone suggested that I replace the oil in the rear end before spending all that money. It has been years and the noise has still not returned.
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Le Mans Master
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From: Maryville TN
St. Jude Donor '06-13,'16-'17, '19
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Race Director
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As the RP in the diff now, easy enough to break out a torque wrench with trans in park/gear, only one side jacked up (other wheel down chocked), and put a torque wrench on the axle nut to see if that side clutch pack slips/axle turns with the wheel up in the air before you hit 100ftlbs.
Note, remember to leave the parking brake off.
Thread Starter
Le Mans Master
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From: Maryville TN
St. Jude Donor '06-13,'16-'17, '19
On another note, when I did the figure 8s, the diff sounded like a coffee grinder!! (Royal Purple) I'll post the difference with the GM stuff when I get it.
Tom
Thread Starter
Le Mans Master
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From: Maryville TN
St. Jude Donor '06-13,'16-'17, '19
Tom
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Thanks for checking the breakaway torque. The 9 lbs low could be your wrench or even be normal since there wasn't a before reading taken. I've used most of the brands over the decades and haven't found any difference, YMMV of course.
Thread Starter
Le Mans Master
Joined: Jan 2001
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From: Maryville TN
St. Jude Donor '06-13,'16-'17, '19
Probably can't do the figure 8's until next Sunday morning when the Mall is closed.
Tom
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From: Aiken, SC
St. Jude Donor '13 thru '26
Question for Dano523. I have 2 new bottles of Mobil 1 75W90 on the shelf with their limited slip friction modifier. Would that be an acceptable alternative to the Dexron??