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no fat GUYS, truck will scrape
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Discussion Starter #1
I heard through the grapevine that the oil used from factory in the newer s-series rear-ends (posi or no-posi) contains alot of detergents and needs to be changed before 70,000km (the sooner the better). Has anyone done this yet, and if so, how hard is it to change??
Thanks!:D
 

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want my #... 911 beotch!!
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i have never heard of that, and would also like to know if it is true seeing as how my truck has 65,000+ miles on it.
 
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well..i don't know about the rearend grease having detergents in it...i know for a fact that the manual 5 spd. trannies have a special grease called syncromesh..... I am not sure if they use that in the rear ends now or not...look in your owners manual..and it will tell you when you should change all of you fluids...i have a 96...and it recommends that you change it every 30,000 miles....it is good habit to change it every 30k....same with tranny fluid and fuel filters and pcv valves...but to answer your question i am not sure...i have seen the new escallades with synthetic oil in them...and they recommend it be changed every 7,000 miles
 

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no fat GUYS, truck will scrape
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Discussion Starter #4
yeah, my synchromesh has already been changed a few times. I don't think they are using it in the rear-ends. The guy that told me about it is a service manager at a GM dealership and he said that it's something that not everyone knows about. They put all the detergents in so that if the truck is sitting at the dealership for a while and not selling, the oil will still be in peak condition . I want to change mine just to be sure, but I want to know how hard it is to change.:D
 

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The Original A D M I N
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ok this is how to change your differential fluid in the rear end of your trucks. Let me start by saying you will get lubricant on the floor. It's unavoidable. If you have been driving your car for any length of time, the lube will be hot, so please be careful and have the oil soak and shop towels handy. Also chock the wheels if you aren't using a lift, and leave the transmission in neutral. Remember to always use automotive jack stands rated to withstand the weight of your car.

Begin by orienting the gasket with the bolts, making sure it is the CORRECT gasket. Next, remove the bolts that hold the backing plate. Notice that there are 2 brackets that also use these bolts. They anchor the brake lines. These bolts are slightly longer than the others, so pay attention to this during reassembly. As soon as you get the bolts out of the bottom, you should begin to see some dripping, so be sure to have the drain pan ready. When all the bolts are out, gently pry or tap the backing plate to get it off. Hang on to it, or it'll wind up in your drain pan. The lubricant should flow out of the housing rather quickly and with a big splash. If you use any oil soak, keep the dust to a minimum as it will get inside your differential housing.

Now its time to clean everything. Most people agree that using your hand to try to wipe off as much of the old lubricant as possible is good enough. There is nothing wrong with leaving a residue of old oil on the gears. I then use paper towels to wipe out all the material from the bottom of the housing. Although you don't have to worry about getting all the old oil out, make sure you get all the old metal shavings out.

Notice what looks like a big washer attached to the plate? That's a magnet and is glued to the plate. Don't try and remove it. Make sure the old gasket is COMPLETELY removed from both the housing and backing plate. Depending on the age and condition of the old gasket you may have to use a razorblade to remove any excess gasket that is stuck.

Put 2 bolts into the backing plate, 1 on each lower side (remember the magnet goes down) and carefully replace the backing plate. Remember the 2 longer bolts go with the brake line brackets and the backing plate is notched to accommodate them. Be careful not to over tighten the bolts.

Use a 3/8 inch drive ratchet to remove the fill/level check plug on the right front of the differential housing. Add the additive first and then fill with the lubricant. This can be tricky, messy and frustrating. I used a small funnel with a clear tube attached so that I could see the lube flowing. You will know its full when you see the oil reaching the top of the fill hole. Once full, replace the plug and you are finished.

I suggest you drive slowly for a couple of miles, allowing the additive and lubricant to mix thoroughly. Stop and check for leaks and after a few miles check the differential level again.

Try using a squeeze bottle with a long nipple to add the fluid. You can pour the additive into the bottle along with the fluid and shake them until mixed. Then use a section of clear motorcycle gas line clamped over the nipple to stick into the rear differential fill hole. This filling method saves a lot of spills and keeps your blood pressure within safe levels.

Hope that this helps. I did this on my 99 last weekend. I should have taken pics, but I did not want to get the camera messy. If you have any Questions then please post them. It should be the same for most year models.

Phiber-Optik
 

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I couldn't have explained it better myself. Great job Phiber :)
 

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no fat GUYS, truck will scrape
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Discussion Starter #7
Wow! Awesome job Phiber. Thanks so much for the info. I am going to do it this winter while it is parked. Any suggestions on a good oil to use??? (I have posi)
Thanks so much!!!!!
:D
 

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The Original A D M I N
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I use redline fluids for my tranny and my rear.

You can use 75W90. The 75W90 is for most street driven and racing differentials. Excellent performance in conventional and limited-slip units. Also for limited-slip manual transaxles which require a 90 WT oil. Contains limited-slip friction modifiers. I also add Redline Limited Slip Posi Additive just to be safe. i know that the 75W90 has the addative in there, but i like to add half a bottle to the mixture.

There are other fluids out on the market that may be a little less expensive than this, but it is my preference. If you do not have the bucks to spend go with the GM Fluids.

This also would be a good time to change gears if you are wanting to get a little performance gain out of your baby. That hole shot jump is nice.
 

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The Original A D M I N
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Ohh and you are welcome. anything to help out the s10 community.

I just did this the other day and should have taken shots of it. normally i photo everything that i do to my truck.
 

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no fat GUYS, truck will scrape
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Discussion Starter #10
That's actually a really good idea. I was planning on changing my gears later on, but I guess common sense would be to only open the diff once:confused: :D Thanks for the reminder. Now all I have to do is decide what gears to go with. I am interested in racing gears because I like the whistle, but I don't even know where to begin. Any ideas??
 

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The Original A D M I N
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sonomagirl said:
That's actually a really good idea. I was planning on changing my gears later on, but I guess common sense would be to only open the diff once:confused: :D Thanks for the reminder. Now all I have to do is decide what gears to go with. I am interested in racing gears because I like the whistle, but I don't even know where to begin. Any ideas??
is this a daily driver? highway driving? a lot of highway driving?

i like 3.73's personally. I did have 4.10's in and that was too much for how i drive. one prob that you will have if you do change gears is your speedo will be off and you will need a hypertech programmer or someone to reprogram your obdII to compensate for this.

For the punch and streetability i like 3.73's but i like to race mine and do not do very much highway driving. best thing to do is find someone you know that has changed gears and ask to drive their truck. That will give you an idea of what you will expect. I am not trying to be flipant on this. i dont want to tell you get this or that. you may not like what i like. My Brother drove my truck and hated the 3.73' said it loses too much top end.
 

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no fat GUYS, truck will scrape
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Discussion Starter #12
What else would I have to do to get the whistle???? I'm sure that only changing gears won't do this........ right? I have heard good things about 3:73s, I think 4:10 might be too high because I do use the highway and I don't want my rpms through the roof. I think I would probably go 3:73s. Are they hard to change?? I would like to do it myself to save the money.
 

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want my #... 911 beotch!!
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i was just wanting to know what would be a good gear ratio that is not as tall as 3.73's but better than the 3.08's i have right now:confused: ? i am planning on changing fluid, gears and swapping out my GM one-legger (i hate that damn thing:bash: ) for a posi:evilg: . what is a good posi that you guys would recommend? and how much do you think it would be for all this? thanks for the help! :drinkhaha
 

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The Original A D M I N
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sonomagirl said:
What else would I have to do to get the whistle???? I'm sure that only changing gears won't do this........ right? I have heard good things about 3:73s, I think 4:10 might be too high because I do use the highway and I don't want my rpms through the roof. I think I would probably go 3:73s. Are they hard to change?? I would like to do it myself to save the money.

it is not that hard to do at all. take your time on it and expect to take about 2 hours. i have done changes in 30 minutes.

you can go with 3.42's and retain a lot of drivability on the road. 3.73's will prolly max you out on the freeway at about 3 grand on the rpm range at 75-80mph or there abouts.

other things that i would do if you are wanting to do the driveline. I would get a good stall converter if you are running an auto. look at a stall of 2600 to keep it streetable. the stock converter wears out quickly on our trucks. i would also add a shift kit. that will firm up the shifting and get ya closer to the chirp in the other gears. go with Redline ATF as well.

if you are running a stick then get a better clutch and fly wheel. i would go with a good aftermarket kit. Stay away from the GM pieces cause they have a tendancy to fail quickly. Go to an aluminum Fly wheel cause you will get more horsepower outof it than the steel factory flywheel. It will improve both useable horsepower and extend engine life. This is achieved because of the lower ammount of rotating mass. you want to go all out then go for a carbon clutch. but expect to pay a ton.

i am an auto guy. i prefer autos for the fact that i can get the better performance out of it and proper shifts by just programming the pcm shift points. i know sticks as well, but they are not my favorites.

phiber-optik
 

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The Original A D M I N
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MightyMouseJ5 said:
i was just wanting to know what would be a good gear ratio that is not as tall as 3.73's but better than the 3.08's i have right now:confused: ? i am planning on changing fluid, gears and swapping out my GM one-legger (i hate that damn thing:bash: ) for a posi:evilg: . what is a good posi that you guys would recommend? and how much do you think it would be for all this? thanks for the help! :drinkhaha
i am an Eaton fan. you will pay a little more than you will for an Auburn unit. But you are getting the quality. Both are real nice and both do what you are looking to do, but if you are looking to race the truck then do Eaton. i have had two Auburns fail at the track. Of course these are my opinions. The Choice is up to you.

As far as Gearing. The 3.73's may be a bit tall dependingon what you are looking to do. If this is a dailydrive and you dont want to loose topend speeds then you can get the 3.42's. That will put your rpm range in the perfet range for highway speeds.
 

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The Original A D M I N
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SonomaGirl: also......to plant the power and get good traction you will want to beef up the rear suspension. There are way too many things that you can do here to make that better. But a good place to start would be to get adjustable shocks. HAL makes a 12 way and they have a model that fits and has enough throw for a lowered truck that is mildly lowered. i have some on mine... i can run out later this evening and look at the part number if you want to go that route. They are a little pricey look at about 165 a shock. there are others out there as well. like the koni's. Remember that you dont want to skimp on the suspension. Serious ways to plant that power would be to go to a 4 link system or IRS. but look to spend serious bucks on that.

Phiber-Optik
 

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no fat GUYS, truck will scrape
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Discussion Starter #18
Yeah, I was already thinking about a 4-link. I like the extra traction and it's good to have if I decide to bag my truck later. I don't think the adjustable shocks would be a great idea because I am already lowered in the back and I will have about a 6" drop after this winter.
My truck is stick, so the shift-kit won't apply.
3 grand isn't that bad for doing 80mph, my b/f's truck does about 4 grand at 80kmh (he's in the process of looking for a new rear-end) I think I could live with that.
I'm gonna look into the flywheel and clutch, and you're right-it is BIG bucks for a carbon-fibre clutch.
Thanks again for all your help......... you definately know your stuff.
Oh, and one more thing, do you know where I can find a tree that grows money????????:D
 

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I'm thinking about changing the rear diff oil this weekend, however when I went to look for the gaskets there are several different sizes for my truck, 97 2wd, 4cyl with 4.10 gears. Any way I can find out which one I have (is there a VIN code?)
 
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