Fluid changes...

**third_shift|studios** · 08-12-2008, 08:06 PM

Replacing all the fluids in the drivetrain....curious if there is anything special i should know/use?

Engine: 10w30 Pennzoil
Tranny: dextrol III
Rear ?????

Do i have to replace the gasket on the rear cover after I crack it open? Do i need GM "posi-adder" or does that come with any rear fluid? What fluid should I use?

**Speedy_Gonzales** · 08-12-2008, 08:13 PM

Originally Posted by third_shift|studios

Replacing all the fluids in the drivetrain....curious if there is anything special i should know/use?

Engine: 10w30 Pennzoil
Tranny: dextrol III
Rear ?????

Do i have to replace the gasket on the rear cover after I crack it open? Do i need GM "posi-adder" or does that come with any rear fluid? What fluid should I use?

I been wanting to change my rear fliud also

**RAWPWR3** · 08-12-2008, 08:21 PM

I think the weight for the rear end is 75w 90, im not sure on what brand to recomend though, im sure some of the oil conosuiers on here will chime in and help you with that.

I would like to know as well cause i plan on putting a rear end girdle on my car soon. Also, some brands of fluid say they already contain the limited slip additive, but i wouldnt just go by that, i think you can purchase the additive through the stealership, im not sure how much they are but it cant be much, its only a few ounces. Oh and yeah, you probably have to replace the gasket for the rear.

**thearborbarber** · 08-12-2008, 08:29 PM

Some people use a gasket, some use just rtv, some use both. I'm in the later category. It mostly comes down to surface prep. The cleaner the better. I also use Mobil 1 75w90 with the posi additive. I use what ever additive the parts store has usually Kedall.

**98Z28importslayer** · 08-12-2008, 08:54 PM

I was told for the rear end royal purple 75w90 was my best bet. I think is also already has addtive in it if im correct ?

**0rion** · 08-12-2008, 11:50 PM

just use regular gear oil and get the additive....any parts store will have it. I use RTV only when I change mine and haven't had any issues with leaks.
Do the tranny filter while you're doing the fluid.

**dparsons1968** · 08-13-2008, 02:04 AM

I just changed my diff fluid last weekend. I used both a filter and small amount of RTV black. No leaks so far (knock on wood). I used the Royal Purple 75W90. O'Reilly's had it cheaper than anyone else here in Augusta.

**sunsetorangess** · 08-13-2008, 03:22 AM

75-90 is what the books call for with an additive, i just used some i got fromt he parts store, no need to get the GM brand.
There is a gasket, costs about 3 bucks plus i would use some rtv to button everything up. Make sure you pick up a pump of somesort to transfer the fluid from the bottle to the diff. Makes things a bit easier.
J

**third_shift|studios** · 08-13-2008, 04:24 AM

is said gasket readily available at parts stores?

**Spaz** · 08-13-2008, 04:30 AM

Originally Posted by third_shift|studios

is said gasket readily available at parts stores?

heh... nothing is in stock when i need it...

**dparsons1968** · 08-13-2008, 04:35 AM

Originally Posted by third_shift|studios

is said gasket readily available at parts stores?

It was for me. $12.50 at the dealer and $3.99 at Autozone. I went with the Felpro brand sold by Autozone.

**Firebirdjones** · 08-13-2008, 04:53 AM

Originally Posted by third_shift|studios

is said gasket readily available at parts stores?

Ya, just your typical 7.5 inch 10 bolt rear that has been used in S-10 pickups and jimmys, malibu's from the late 70's and early 80's etc....Monzas and Vegas from 71-80......in other words it's been around for a long time and has many applications,,,,just about any parts store should have the gasket in stock.

Just a little side note: You'll know if the rearend has ever been apart before when you crack open the cover. Check the gasket closely,,,if there are 2 gaskets used on the cover,,,,then it's never been apart.

GM has doubled the cover gaskets on rearend covers since the 60's and they still do it today

**Spaz** · 08-13-2008, 04:56 AM

Originally Posted by third_shift|studios

Replacing all the fluids in the drivetrain....curious if there is anything special i should know/use?

Engine: 10w30 Pennzoil
Tranny: dextrol III
Rear ?????

Do i have to replace the gasket on the rear cover after I crack it open? Do i need GM "posi-adder" or does that come with any rear fluid? What fluid should I use?

i'll give you $1.00 if you get video of you huffing the old rear gear fluid...

**Sarge** · 08-13-2008, 06:04 AM

Here are my thoughts.....
Rear End...use any GM certified fluid if your going to change it yearly. Use Amsoil w/friction modifier if your not. Royal Purple loses viscosity rather quickly.
Trannie. I use Valvoline DexIII but once again I change it every year with a flush machine. If your not going to flush it every year then go with Amsoil.
Engine. I've beat that one to death

**Firebirdjones** · 08-13-2008, 11:25 AM

Just to add sarge,,,,Valvoline doesn't make a dexron III in synthetic that I am aware of.

Just thought I'd add that since most people here are hooked on synthetic stuff.

I've only been able to find Dexron III tranny fluid in synthetic in either Mobile brand, Royal Purple,,,,maybe one other brand I am missing.

Edit,,,I would like to check out amsoil oil but that stuff is harder than hens teeth to find around here. None of the big parts chains seem to carry it.

**Zboner** · 08-13-2008, 11:30 AM

Originally Posted by Firebirdjones

Just to add sarge,,,,Valvoline doesn't make a dexron III in synthetic that I am aware of.

Just thought I'd add that since most people here are hooked on synthetic stuff.

I've only been able to find Dexron III tranny fluid in synthetic in either Mobile brand, Royal Purple,,,,maybe one other brand I am missing.

Edit,,,I would like to check out amsoil oil but that stuff is harder than hens teeth to find around here. None of the big parts chains seem to carry it.

as far as I know no one in the Cincinnati carries Amsoil

**Firebirdjones** · 08-13-2008, 11:39 AM

Originally Posted by Zboner

as far as I know no one in the Cincinnati carries Amsoil

Ah okay well that explains it then,,,,since we are both from the same area. I've been all over and have never seen it sold anywhere.

Although here in Bethel there is a local shop that advertises they use amsoil,,,but it's not sold individually to the public,,,you have to bring your car in for service

**Sarge** · 08-13-2008, 11:47 AM

Originally Posted by Firebirdjones

Just to add sarge,,,,Valvoline doesn't make a dexron III in synthetic that I am aware of.

Just thought I'd add that since most people here are hooked on synthetic stuff.

I've only been able to find Dexron III tranny fluid in synthetic in either Mobile brand, Royal Purple,,,,maybe one other brand I am missing.

Edit,,,I would like to check out amsoil oil but that stuff is harder than hens teeth to find around here. None of the big parts chains seem to carry it.

I know that

I use conventional as I flush it every year.
You get Amsoil from CompSyn....the Amsoil sponsor here on the board.

**Sarge** · 08-13-2008, 11:48 AM

Originally Posted by Zboner

as far as I know no one in the Cincinnati carries Amsoil

Get it from here frog....
http://www.competitionsynthetics.com/

**Firebirdjones** · 08-13-2008, 11:55 AM

Thanks for the links. I just wish I could pick it up myself locally. I have been avoiding mail order stuff lately. With gas prices up it seems everyone is raising shipping costs as well, which drives the overall price up

One place I haven't checked is the only local speed shop left on this side of town,,,,I have to stop in there for some carbuator parts,,,I'll check and see what oils they sell.