Hemi Killer

iTrader: (6)

How often are you supposed to change the differential fluid & transmission fluid?

I have my oil & oil filter changed every 2500-3000 miles. I'm thinking about switching to mobil 1 synthetic. Would it help me out any?

I just found out a month or two ago that you are supposed to change the fuel filter every 15,000 miles. When I found this out I already had 4x,000 miles on it

If there is anthing else please let me know! Thanks!

hodgeee

Diff oil, and transmission oil, according to GM should be replaced every 30,000 miles, or anytime your differential has been submerged under water, like when putting a boat into the lake(this applies only to the axle, not the tranny). Now most 4x4s have a hose attachment from the breather valve on the differentials, that goes up to the frame and even when submerging the axle, no water gets in. A lot of mechanics will say change the diff oil every 60,000 since it is a heavy oil, but I believe, just like any other oil, it breaks down after time. I replace both of mine every 15000 miles, since I beat on my vehicles. I just had a gear change with only 6000 miles on my truck, and I had burnt the races and bearings on my truck, and had them all replaced! To refill your diff, only costs about $18 if you do it yourself, and that includes friction modifier if you have a limited slip. I beleive in doing transmission flushes only, not the drain and fill and replace the filter crap, that only changes between 1/3 to 1/2 of your oil. A good price for a tranny flush for a 2wd is about $85, anything over $105 is a rip off. I am also a firm believer to not use synthetics in your transmission or differentials. Every transmission expert I have talked to says that the synthetic oils that they make for diffs and trannys has a different consistancy than the regular oils, does not flow the same, and can make the parts work slightly differently. They say that the tranny, and limited slips are designed to work with conventional oils, and synthetics could cause extra slippage in limited slips, and can cause problems with the flow rates of valve bodies in transmissions.

I know that the oil weight rating on the bottle is supposed to indicate how the oil flows, but I have read and heard several times that they flow differently.

Now for motors, I am a firm believer in using synth oils, and it has been proven to work fantastic for wear properties, and you are talking a simple pump systems. Sorry to blabber on. Just spewing info from my mechanic days.

Slowverado

hodgee...how hard is changing the diff oil? i've got 60,000 on mine and it's been abused with the best of'em and has never been changed. the tranny fluid should be new since it's a relatively new tranny. but the diff has me worried now seeing that you should do it every 15k

CashDudeHomie

iTrader: (5)

Its easy. Theres a drain plug on the bottom and a fill plug on the top. Use a 3/8 ratchet to open them. You probably should pull the cover off and clean the magnet but you don't have to.

Yelo

how did you come to the $18 price for the rear-diff fluid change ?.....my gasket was $14, the friction modifier was $9 and the gallon of synthetic gear oil that GM calls for was...yes, this is right.....$45, and that was from Carquest....not the dealer

I try to change the fuel-filter every 10,000-15,000, the front diff every 20,000, and the rear diff....well, whenever I can see spending $70 on oil and a gasket....usually every 30,000

Slowverado

i had 50k on mine before i changed the fuel filter and it was like a new truck when i did change it. there was a definate performance improvment from just that. as far as the diff fluid, so drain the fluid out the bottom(open top to vent) and then pull the cover to clean up inside right? pulling just the cover wont effect the gears or anything inside will it? thanks guys. maybe i'll just wait and buy a new eaton and some 4.10s and let FORT WORTH GEAR AND AXLE do it.

Hit Man X

I change ATF fluid around every 15K. Just drain the pan and fill 'er back up. No point in changing the screen as it never really gets dirty anyway. A flush is better but costs a bunch.

Fuel filter every 10-15K also.

Front diff, rear diff, and transfercase around every 50K. Just drain and refill.

Oil 3500-4500mi, depends on color of it and if I am running Dino or Syn.

CashDudeHomie

iTrader: (5)

I did my own flush. I bought some rubber hose and stuck it where the filter goes and stuck the other end in a gallon of transmission fluid and start the truck for about 5-10 seconds until it sucks all the new fluid in. Oh yeah put a huge drain pan under the valve body. I did that with 3 gallons. I hope it did some good.

LS1csherm

Might want to check your owners manual
My '03 comes with syn oil already in the diff.
I have been running syn oil in my 91 silverado for 12 years - I change it every 3 mons or 3k - my oil press went up 15 psi
In the diff I run Mobil 1 - truck has 110k - never had a prob.
I also switched my '03 over to Mobil 1 - same results oil press went up.
I will prob change the rear diff at 30k - but will use Mobil 1 again

The syn issue with a rear diff is 100 untrue - as my '03 comes with it in the diff from the factory.

MarineBlue03GMC

So at what point does everyone think I should change my 03's tranny fluid? I have almost 10,000 miles now.
Should I change it now or wait till 15K?