'break-in' after changing diff fluid?
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Joined: Mar 2012
Posts: 56
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From: San Antonio TX
'break-in' after changing diff fluid?
I've read from somewhere that after changing the diff fluid in the car, you should drive gently and refrain from WOT for at least 300 miles. I've also read that you should do some figure 8s in a parking lot.
What is the reasoning behind these, and what is the truth as to what is necessary to have the fluid/diff completely 'broken in' and ready for an autox event or track day?
I went and did some low-ish speed figure 8s in a parking lot, not a huge deal. I'm not sure if the reason for doing this is simply getting the wheels to move at different speeds, in which case it probably helped, or getting enough lateral loads to push fluid to one side or the other, in which case I probably didn't do much.
Also, the 300 miles thing is going to be difficult in a car I don't drive every day. I'm at 160 miles right now since the change, and thats with two trips just for the purpose of adding miles.
So whats the truth here? While any input is welcome, documented/researched info would be appreciated.
Thanks,
Jason
What is the reasoning behind these, and what is the truth as to what is necessary to have the fluid/diff completely 'broken in' and ready for an autox event or track day?
I went and did some low-ish speed figure 8s in a parking lot, not a huge deal. I'm not sure if the reason for doing this is simply getting the wheels to move at different speeds, in which case it probably helped, or getting enough lateral loads to push fluid to one side or the other, in which case I probably didn't do much.
Also, the 300 miles thing is going to be difficult in a car I don't drive every day. I'm at 160 miles right now since the change, and thats with two trips just for the purpose of adding miles.
So whats the truth here? While any input is welcome, documented/researched info would be appreciated.
Thanks,
Jason
Race Director
Joined: May 2004
Posts: 15,866
Likes: 196
From: PA
Im not even sure I did any break in when I installed new gears in the rear of my old 97 z28? I've never heard of any sort of break in procedure for just changing the rear fluid in any car. I've changed the fluid in mine and other cars and never did any sort of break in. New brakes require a break in period, clutches also. I wouldnt worry at all about just changing the rear fluid though. 
Team Owner
Joined: May 2001
Posts: 87,323
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From: Western NY
....I've never heard of any sort of break in procedure for just changing the rear fluid in any car. I've changed the fluid in mine and other cars and never did any sort of break in. New brakes require a break in period, clutches also. I wouldnt worry at all about just changing the rear fluid though.
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Tech Contributor
Joined: May 2008
Posts: 3,100
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From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
What's so unique about the Getrag differential to require no WOT for 300 miles after a simple fluid change?
I agree with doing the figure 8's however. This helps to distribute the new fluid into the limited slip clutches.
Tech Contributor
Joined: May 2008
Posts: 3,100
Likes: 17
From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
The use of synthetic gear lube is specified by GM.