Diff Fluid Question!!!

[98EBinMO]

Hey, I know this has been talked about a zillion times- but I am REALLY ****-retentive (especially with my vehicles) and want to make sure I did it right...

I changed the diff fluid tonight- pulled the cover, cleaned it off, Black Siliconed the cover- let it wait- siliconed the bolts and snugged the cover...

I let the cover dry for about 2 hrs. before I refilled it- I put in a full thing of limited slip additive (7 oz.) and a little less than three quarts of fluid... there wasn't any fluid running out of the hole, and I couldn't tell if I could put my finger in it; I had so much on my hands

What I am wondering is if this sounds OK, or if I need to buy another quart of fluid... from what I have read, this should be a full fill...

THANKS FOR ANY AND ALL REPLIES!!!

 

[98EBinMO]

Anybody out there?

Come on ya'll- anybody done this lately???

 

[taxx]

Put the fluid in until it starts to run out of the hole. And according to Randy's Ring and Pinion regaring LS fluid:

With regards to limited slip additives, I have found that using too much additive can lead to premature gear wear. Use just enough to keep the limited slip from chattering but not more than 4 oz for every 2 qts of oil. It is a good idea to change the gear oil after the first 500 miles in order to remove any metal particles or phosphorus coating that has come from the new gear set. This is cheap insurance and a good time to discover any problems before they grow to disastrous proportions.

So it looks like you are a little on the high side of the LS additive but not too much. Once you fill it up with more diff fluid you should be good to go!

 

[98EBinMO]

Thanks Taxxman2k,

I just got it back from the local quick lube...

I had them check the rear fluid after the pumped out the front...

They said it was right on- but now I'm worried about the 6.5 ozs. or so of LSD additive I added... (I dripped a little putting it in...

I hope the little extra doesn't hurt anything...

Anybody else wanna join in with experiences, etc...???


THANKS!!!

 

[taxx]

If it is only 6.5 OZ then I would say you are alright. If you do the math the ratios are not even off by a half of a percent.

 

[98EBinMO]

whew!!!...

taxxman,

thanks for the reassurance... what is the ratio you are referring to?...

By the way- the fluid I put in was Valvoline Synthetic Blend 75-140... It was $4.39 a qt. and was the only 75-140 I could find local that wasn't cheapo stuff...

Besides, I will probably change it again in about 50-60,000 miles (if I have it that long!!!)

Anyway, thanks for your quick replies...

 

[taxx]

By ratio I figured Randy says 4 ozs to 2 quarts (there are 32 ounces in a quart), so the ratio of additive to fluid is 4/64 you have about 6.5/96.

4/64 = 0.0625
6.5/96 = 0.0677

So it is only .52% difference. Somebody may want to check my math, but that looks right.

 

[Robert]

My '97s manual lists the rear capacity at 5.50 - 5.80 pints and calling for 4 oz. of friction modifier for limited slips.

 

[taxx]

Originally posted by Robert
My '97s manual lists the rear capacity at 5.50 - 5.80 pints and calling for 4 oz. of friction modifier for limited slips.

I would go with what Ford recomends, Randy may be right but his is a MAXIMUM.

 

[SplashMan]

Do you really need the friction modifier, if you change to synthetic gear lube? Just wondering, because I am changing the rear this weekend and thought I could go without the modifier if I went with synthetic.

 

[taxx]

Originally posted by SplashMan
Do you really need the friction modifier, if you change to synthetic gear lube? Just wondering, because I am changing the rear this weekend and thought I could go without the modifier if I went with synthetic.

I don't know but my best uneducated guess would be yes you still need it. Call a driveline shop in your area and ask what they think, if no one here knows the answer.

 

[98EBinMO]

Friction Modifier...

Hey, I'm back!!!

Just wanted to mention that the friction modifier I added was K&W brand I bought at Autozone...

It said to add the entire bottle (7ozs.) to the differential.

I assume the Ford brand is "more potent" or something- anyway, it said it was a direct replacement for the Ford fluid- and it was handy to get all the stuff at once...

I am also interested to see how the Semi-Synthetic fluid will work out- I've heard you don't need to add modifier to true synthetic fluid, but I don't know about semi-synthetic... I figure it won't hurt to add it to be sure.

Also, I the quick lube shop told me that it is better to leave the level about 1/4 inch below the fill hole to allow expansion... I don't know, but I added what is recommended (what I could suck out of 3 quarts with a $10 fluid pump from Autozone + the friction modifier) so I'm not gonna worry about it...

Thanks to everyone who replied- I REALLY APPRECIATE it!!!

 

[Robert]

It isn't the fact that it is "true synthetic" that you don't need the friction modifier. It is because the "true synthetic" already has the proper properties. Not all "true synthetics" have the proper properties to not need friction modifier. I have only heard of one that states that friction modifier is not required. I can't remember for sure but it was either Royal Purple or Amsoil. If the spec. sheet or bottle doesn't say that friction modifier is not required, then it needs to be added or else your limited slip will not work properly.

Regarding the lube shop's comment that it is better to leave the level 1/4" below the fill hole to allow for expansion couldn't be further from the truth. The fill hole was placed where it was for a reason and Ford has determined the right amount of fluid for your differential. The correct procedure is to fill it up until it runs out. There is still plenty of room for expansion. If it needs more, that is what the vent tube is for. Running it lower than the recommended level can cause your differential to quickly overheat and trash all sorts of expensive parts. Granted 1/4" probably isn't going to matter much, but it still isn't the proper amount.

 

[crivas13]

Hi,

I just changed mine this weekend with Mobil 1 75W90 and i added the 4oz. of the ford modifier and it took all 3 quarts and it still didnt spill out. I ran it and checked it again and if i put my finger in there it comes out full of oil but it doesnt spill out. Should i buy another bottle and add until it spills out?

Thanks,
Carlos

 

[dogfriend]

Originally posted by Robert
It isn't the fact that it is "true synthetic" that you don't need the friction modifier. It is because the "true synthetic" already has the proper properties. Not all "true synthetics" have the proper properties to not need friction modifier. I have only heard of one that states that friction modifier is not required. I can't remember for sure but it was either Royal Purple or Amsoil. If the spec. sheet or bottle doesn't say that friction modifier is not required, then it needs to be added or else your limited slip will not work properly.

I used Redline Syn 75W90 in my 89 Ranger, and they stated at that time that friction modifier wasn't needed for limited slip with their oil.

 

[vbtruk]

Hey guy's i want to change my diff fluid this week with the tranny and am going to use AMSOIL on both do i need a friction modifer? and would the ford one be ok with the amsoil?
i have a 4x4 SOHC 4.0L V6
thank's.

 

[dogfriend]

I found this:Dead Link Removed

They state that friction modifiers are not necessary.

I would try it without, if you need to add it because of chattering while turning corners, you could always add some later.

 

[vbtruk]

ok cool, by the way 1) when i change the trasfer case fluid do i need to add any additives like the diff???
2) And which viscosity Gear lube should i buy from AMSOIL???
3) is the Universal Amsoil Tranny fluid my best bet for the tranmission flush and filter change????
Thank's in advance guy's.

 

[dogfriend]

NO! Don't add any friction modifiers to the transfer case!

Check your owners manual for fluid type, but the Control Trac transfer case uses ATF, not gear oil. Im pretty sure that the AWD case also uses ATF.

 

[98EBinMO]

This thread is still alive! COOL!!!

I started this thread looooong ago, and glad somebody else had q's about this stuff- wish I had gone with Amsoil- although it would have been ALOT more expensive! I went with the Mercon V (which I hear is semi-synthetic) and it was about $2.50 a qt. for the 14 qts. that are changed on my V-8's tranny and another couple for the transfer case. My total bill (with labor) was around $110 (filter, fluid and labor).

Also, I ended up adding K&W to the rear differential per the instructions on the container and haven't had any problems since...

GOOD LUCK!!!

TOBY

P.S. This is an awesome site and thanks to all those that participate!

vbtruk- Are you doing the change yourself or having a shop do it?