Rear differential fluid change?

SB09 · March 6, 2015

Does anyone think 30K miles is a little fast for my rear diff fluid to be dark and dirty looking? The oil change place inspected it I guess and came out with a sample of the fluid telling me it needs to be replace. I've never done a fluid switch this quick(37k) on any truck I've owned. I'm wondering if theres a bigger problem developing that I'm missing. They could have just been trying to squeeze money out of me, I will pay nobody $80 to do something this simple. I am going to purchase the oil myself and change it I guess. Hopefully this isn't the normal operating procedure for this truck. I went 75k on my previous Chevy trucks no problem before the fluid looked anywhere near dirty.

redwngr · March 6, 2015

Sounds like they are playing you.

gone_fishing · March 6, 2015

When I changed the fluid in my Sierra's rear axle it was also quite dark. I doubt the fluid is bad simply because it's dark. I was more concerned about getting the break in metals out.

See this post of mine for more details: http://www.gm-trucks.com/forums/topic/164726-rear-axle-fluid-change-completed-at-23680-miles/?do=findComment&comment=1503530

fondupot · March 6, 2015

Just because oil is dark doesn't necessarily mean its bad. They are just trying to get your money.

Gmcant33 · March 6, 2015

30k? They must be high I usually go up to 100k for change watch out for those rats

Mossyoakglock · March 6, 2015

Has it ever been changed before?

If it hasn't it can't hurt to do it and get all the breakin metal particles out of there. It only take a little over 2 qts so it shouldn't cost you that much anyways.

07Softail · March 6, 2015

It should have been changed at the first 5000 miles after the break in heat cycles. Ring and pinion gears are one of the most abused parts on a vehicle not mentioning the bearings and clutches for your limited slip. Every 15-20K is normal changing intervals. You guys spend thousands of dollars on Tuning, CAI's, Headers, cat-back exhaust, rims, lift kits, lowering kits, blowers, cams, Window Tint and won't spend $20 on 2 quarts of Damn gear lube! GEEZ!!!

EDIT: This was not directed at the OP... just the NAY SAYERS!!

RT

Jake56 · March 6, 2015

be careful because if your truck has limited slip then it may use speciality fluids , these fluids may look different colour than what a kid at a drive thru oil change place is used to seeing , A dealer might give you better info to base this decision on.

fondupot · March 6, 2015

be careful because if your truck has limited slip then it may use speciality fluids , these fluids may look different colour than what a kid at a drive thru oil change place is used to seeing , A dealer might give you better info to base this decision on.

Do any GM trucks even come with a limited slip? I thought they are either all open diffs, or the Auto locker?

GMC-AT · March 6, 2015

what does the owners manual ( GM engineers) suggest? probably a good place to start!

galliher_nc · March 6, 2015

what does the owners manual ( GM engineers) suggest? probably a good place to start!

GM recommends changing it every 30k, IIRC. Same with the transmission fluid.

07Softail · March 6, 2015

Do any GM trucks even come with a limited slip? I thought they are either all open diffs, or the Auto locker?

Limited Slip, Posi, The Newer G80's are clutch type differential units. This crap we have in the present day all the way back to the late 80's are Gov locks and have clutch plates and are in NO WAY LOCKERS so don't get them confused. True Lockers pop when turning because they have interlocking side gears. So limited slip is just a loose term.

RT

thewhitestallion · March 7, 2015

is it too soon to change, eh maybe, maybe not, that is subjective though. is it going to hurt to change the oil in your diff. no. but in all honesty I would not worry about it too much. not saying this is how it is suppose to be done, but I went around 100k in my gmt 800 before replacing both the tranny and diff fluid. however that truck never saw a trailer or heavy abuse.