Synthetic

[Roofer]

I use synthetic engine oil (Mobile 1), but have not changed out any other fluids on my truck. Anyone change out any other fluids? I am close to 30,000M, so I am wondering what others have done for maintenance.

Thanks

[Zane]

I've heard that transmission and rear diff fluids should be changed, but i'm not sure at what interval.

[JohnGMC]

Roofer,If it were my truck,Id go ahead and change every fluid in the truck,but thats me,I keep trucks for a while and have access to a lift,so its not a big deal,and i enjoy working on my truck,performing maintance and upgrades.I would change both front and rear diff fluid,T-case,and service the tranny.Then id flush the P/Steering and put new fluid in.I would replace the brake flid next year,and the dex-cool will last a while longer yet too.After this I would leave everything alone until 100K,except the tranny,service it every 30ooo if you have an aux cooler,sooner if you dont.The break in oil is still in every component in your truck,except the engine,when beaking in filings and heat are higher than normal,it is smportant to flush these contaminants out to ensure long life from the drivetrain.It  will cost about 50 bucks in parts to change every fluid in the truck-you have no idea how much this could save you 4 years down the road.I love PM-it pays you back ten-fold

[MountaineerTom]

I'm at 20,000 on my '99 and I'm planning on changing out the diff fluids on the first weekend that I get the chance.  I'll probably wait a little while longer on the tranny since I don't do any towing.

[Roofer]

Thanks guys!! If you don't mind, could you sometime explain this a little better. I have never touched anything except engine oil. Or should I have the dealer do it?

Thanks

[MountaineerTom]

The diff fluid is really easy.  Some people only remove the drain plug, let drain and refill it.  I prefer to drain it, remove the rear end cover, inspect for any signs of damage, put a new casket on with the cover and refill it.  This is my first 4X4, so doing the front will be new to me.  I guess after removing the skid plate for easier access, it will be about the same.  

The tranny shouldn't be that hard either.  If yours is like mine, it has a drain plug also.  My '91 Chevy didn't, and that was a mess.  It drained all around the pan as you were removing the bolts.  I think both the diff's and the tranny have a magnet to collect small metal particle's, so you would want to clean that off.

Tom

[Roofer]

Thanks Tom. Sounds easy enough. Does the owners manual state ho w far to fill these? Also which brand is decent, Mobile 1?

Thanks again

[MountaineerTom]

This is what the owners manual says for my '99.  I'm not positive, but I imagine the '00's would be the same.

REAR AXLE - The proper fluid level for the 1500 series is from 5/8 inch to 1 5/8 inch (15mm to 40mm) below the filler plug.  Add only enough fluid to reach the proper level.

FRONT AXLE - When the diff is cold, add enough lubricant to raise the level to 1/2 inch (12mm) below the filler plug hole.

When the diff is at operating temperature (warm), add enough lubricant to raise the level to the bottom of the filler hole.

As far as which brand, everyone has there own preferences.  I think most people use the Mobil 1 gear oil, which is a great product.  I like to use Valvoline products myself.  By the way, the owners manual calls for 75W-90 synthetic for the rear and regular 80W-90 gear oil for the front.  I guess you could still use synthetic in the front though.

(Edited by MountaineerTom 99Z71 at 10:22 pm on Feb. 8, 2001)

[Shaners]

The rear diff. fluid should be changed after 500 miles of towing.  If you don't tow GM doesn't think it is in need of changing, and I don't believe there is another recommend change for some time.

I just had the transfer case changed at the dealership.  He did it for free because there is a bulliten out about it.  I told him I had slight vibration and noise while under acceleration in 4x4 high and he checked the computer and it told him to change it and then change it again after at least 150 miles.  So I've had it changed twice now.  I believe they fill it with synthetic.  

As for engine oil, I'll just run Pennzoil at the reccommended weight and AC delco filters.  I probably won't keep this truck past 50k miles and I know with regular oil changes, the motor will last close to 3 times that with regular changes and no major abuse.  I'm sticking with the AC/Delco filters because I've heard of problems with aftermarket filters and 5.3L engines.  I only have 1750 miles on my truck, so I haven't changed the oil yet, but my dealer will do it in 30 minutes or less for ?.95.  That beats the crap out of doing it myself!!!  No mess/old oil/old filter...  no trip to the store to get the stuff I need, and I don't have to change my clothes!!!

[JohnGMC]

Roofer,the front axle is easy,just a 13 and 15 mm wrench needed,drain is under the diff,drain it warm,run it in 4wd ofr a few miles,then drain it-if you can,fill from fill hole at the top.The rear end,you have to remove the 10 bolts on the cover,remove the cover,with a drain pan,under it.scrape the gasket,get a new one from the gM or Napa dealer,I use fel-pro,then install cover with new gasket.On pass side of pinion there is a plug that your 3/8 drive ratch will fit right into,remove it and fill it to the point that its level with the bottom.T-case is easy,it has a fill and drain plug.tranny is messy,if your not careful,remove all bolts form pan except 2 across from each other,loosen one of them a turn or 2 then the other loosen the same,smack the pan with  rubber mallet of a hammer a few times to break the seal,once it starts leaking then remove the one bolt slowly and let the fluid run out,after it stops,remove the other and pull pan,replace gasket,and replace filter,put up and torque bolts evenly,go over the bolts a few times,they will lossen as you torque the next one.Put 4 quarts in the fill tube,then fire it up,check the level,add if necessary-thn test drive,and check it again.

[Roofer]

Wow John, it is way more work than I thought it would be. I like the drain plug idea on the front axle. I wish the rear and the tranny were the same. I'm scared I will screw something up.

[JohnGMC]

It is well worth your time if you plan to keep the truck much beyond the warranty and work it any where's near as hard as i work mine,which is hard.If you cant do it,most shops will service the trans for 49.95 and the rear about the same-have a shop you trust do all the fluids if you want,but if your going to just run it,at least have the tranny done.

[Frank S]

Man,I'm glad my rear differential has a drain plug.I'm not sure about the tranny though because I haven't pulled the skid plate yet.

[MountaineerTom]

My '99 has a drain plug on the tranny pan and the rear diff.  The one on the tranny pan is near the drivers side front corner of the pan and the rear diff drain plug is right on the bottom of the diff.

[Black02Silverado]

Was traveling back in time and found this way back in the back of this section.

 

Just goes to show if you have a question, do a search and more than likely you will find an answer.

 

This is one topic that never seems to go away.