Differential fluid change

[Thub]

I am looking at changing the fluid in my rear differential, the truck is a 2002 4x4 xlt, i have the towing package so im sure its a 3.73. I have the classic whine and am hoping some new fluid will help quiet it down a bit. I know what i need to do the only part im worried about is getting the proper fill level. I have read that you fill to the fill plug and then remove the abs sensor bolt and add another pint, is this true or is to the fill plug good, its seems kinda low to me. I know the manual says 1.8 pints or whatever.

Also i plan on using mobil 1 75w-140, should i use a different brand or not. I've heard nothing but good about mobil products.

 

[Thub]

oh and i also took a look to see where this speed sensor was located and it looks pretty tight, i don't know how the hell you get a socket up in there and unbolt it.

 

[Ronin8002]

I am looking at changing the fluid in my rear differential, the truck is a 2002 4x4 xlt, i have the towing package so im sure its a 3.73. I have the classic whine and am hoping some new fluid will help quiet it down a bit. I know what i need to do the only part im worried about is getting the proper fill level. I have read that you fill to the fill plug and then remove the abs sensor bolt and add another pint, is this true or is to the fill plug good, its seems kinda low to me. I know the manual says 1.8 pints or whatever.

Also i plan on using mobil 1 75w-140, should i use a different brand or not. I've heard nothing but good about mobil products.

The mobil1 75w-140 will be fine. Not sure if it will help the noise though...I don't know if anything does other than a rebuild.

I heard the ABS sensor thing too but when I did mine I was going off of the 1.8 pints as a guide. That got me to the bottom of the fill hole and I left it at that. If you fill it up higher then I guess you just add a pint to that.

 

[Thub]

yah when i looked at the diff it just seemed like the fill hole is so low and that the diff will only be 1/4 full of fluid. but i guess if i hit the fill spec 1.8 pints then what ever.

 

[Ronin8002]

yah when i looked at the diff it just seemed like the fill hole is so low and that the diff will only be 1/4 full of fluid. but i guess if i hit the fill spec 1.8 pints then what ever.

Yeah that confused me too but it's not like the gears have to be totally submerged to the top to get lubed. Besides it keeps the oil level around the same height as the axle seals...you'd think adding too much would lead to leaking around there but maybe not.

Anyway It must be something that they changed in the procedures later on because I can't find it referenced anywhere in my shop manual or anywhere else other than what someone on here told me.

 

[Thub]

yah I figured it will get all splashed around inside there anyway.

One other thing, If i get the mobil 1 LS fluid should i still add the ford friction modifier or not, i have read some guys say add it otherwise you will get the chatter.

 

[Ronin8002]

Not sure, supposedly it's already included in the formula. You could try it without and see. Or just add in the friction modifier from the get go for peace of mind.

 

[Exproblems]

yah I figured it will get all splashed around inside there anyway.

One other thing, If i get the mobil 1 LS fluid should i still add the ford friction modifier or not, i have read some guys say add it otherwise you will get the chatter.

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You only have to add the Friction Modifier if you have a "Limited Slip" rear diff. Otherwise, the Mobil 1 75W-140 is all you need for an "Open Diff". Check your drivers door "Specs sticker" and look for an "Axle" tab, and they'll be a number or number and letter combo code under it. You said you think your gears are 3.73, but that gear ratio comes in both open and limited slip. The Open Diff for 3.73 gears is code #46 and the Limited Slip code is "D4". The axle codes go like this #42, 45, 46 are "Open Diff" and D2, D4, D5 are Limited Slip. The Haynes manual calls for a rear diff fluid level of 1.60 qts to 1.75 qts or in my book, fill it till it starts to spill out the fill hole with the vehicle level at the time of fill. BTW, my Ex is the V-6 with a Class 2 towing package and it has code #45 axle/diff or 3.55 gears "Open Diff". Also, the 3 gear ratio's 4.10, 3.55, 3.73 come in both Open and Limited Slip versions.

"

 

[Thub]

I have the class 3 hitch so towing package, must be an limited slip then but i'll check to be sure.

 

[Exproblems]

I have the class 3 hitch so towing package, must be an limited slip then but i'll check to be sure.

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If you do need it, the Friction Modifier comes in a 7 ounce squeeze tube, costs about $5-$6 and you can get it at parts stores besides the Ford dealership. If you have an Advance Auto Parts store near you, you might be able to order the gear oil online at their web site and select to pick it up at their store. Try using an online coupon from www.couponcabin.com for Advance Auto parts, between the 2 qts of Mobil 1 75w-140 at approx $18.95 a qt and the Friction modifier, you might be near a $50 order. Advance has a $20 off coupon on orders $50 and over. Might save you $20. Let me know if you try this, not sure if you can order gear oil with the coupons, engine oil you can't because they have in store specials all the time on oil change stuff.

 

[dwcopple]

I got the rear diff fluid changed to Royal Purple at a local Pennzoil 10 minute oil change place for $45. It completely stopped the chatter from the OEM fluid.

 

[Exproblems]

I got the rear diff fluid changed to Royal Purple at a local Pennzoil 10 minute oil change place for $45. It completely stopped the chatter from the OEM fluid.

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Thats a low price for that service. Is Royal Purple 75w-140 a "full synthetic" gear oil? If so, what does a quart of it cost? Would have to buy 2 quarts of it to change the rear diff fluid. I was quoted $100 for the rear diff service at a Valvoline Instant Oil Change shop here.

 

[dwcopple]

Every Royal Purple product is full synthetic. A quart is around $18-20. It was a no brainer.

 

[Exproblems]

Every Royal Purple product is full synthetic. A quart is around $18-20. It was a no brainer.

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Just curious here. How did you get the rear diff fluid change at that Pennzoil oil change place for only $45 then? 2 Quarts of Royal Purple would cost $36-$40 to do the rear diff (Holds 1.75qts) and the cost of any friction modifer you may have needed if you have limited slip diff . Where is the labor profit for the oil change shop? They lost a ton of money if they did it for $45. Oil change shops usually prop up the price for quarts of brand name oils than what you can pay for them yourself at a parts store.

 

[dwcopple]

$5 off coupon for one. That and you don't need a modifier with royal purple. If you think a retailer pays that much for their oil you are nuts. They probably pay somwhere around $8-10 a qt for this. Labor? Undo a drain plug, undo a fill plug, reinstall drain plug, fill, reinstall fill plug. Took ten minutes. They made their $$$.

 

[Exproblems]

$5 off coupon for one. That and you don't need a modifier with royal purple. If you think a retailer pays that much for their oil you are nuts. They probably pay somwhere around $8-10 a qt for this. Labor? Undo a drain plug, undo a fill plug, reinstall drain plug, fill, reinstall fill plug. Took ten minutes. They made their $$$.

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I'm well aware retailers don't pay retail price for the products they sell and charge to you, the customer. But they usually make their money off of both the price mark-up for parts/supplies and the labor time charge, which is figured into the type of service you are having done, which has to pay the salaries of their employee's and the other shop overhead they have to pay out as well. If they made any money on you, it wasn't much at all, if any. They basically did the job for nothing. Even with your $5 off coupon, "$45" for the rear diff fluid change using premium priced gear oil just sounds hard to believe. I paid $18.95 +tax per quart (2) for Mobil 1 75W-140 at a parts store, same price you stated for a quart of Royal Purple, so around $40 just for the gear oil just to do it myself. So, this Pennzoil shop did the rear diff fluid change for an extra $5 on the labor part of it or $10 if you didn't have a coupon? BTW,these oil change shops will still charge you full retail price for the oil you buy from them. Oil change places were charging $39.99 for rear diff fluid changes 10-15 years ago and that was using generic, cheaper, 55 gallon drum gear oil, not premium Royal Purple. I know this because I've had this service done on my vehicles at these places back then. Don't forget the rise in inflation for the last 10-15 years. Also, what you or I consider "simple or nothing" for labor service time like removing a drain or a fill plug, they don't! Ever hear how much they want to install parking light bulb or head lamp, try at least $10-$20 plus the marked up price of the bulb. They even charge $60 min to install a serpentine belt which only takes 5 minutes to remove and install. The belts run around $25-$30 themselves. So they get $30 to put it in. Like I said previously, I was told $100 for a full synthetic read diff gear oil change at a Valvoline Instant Oil change shop, a national chain just like Pennzoil. You must live in the discount state.

 

[dwcopple]

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You must live in the discount state.

Nope. Just a smart shopper. Link to coupons...
http://www.pioneerquicklubes.com/coupons.htm
reg prices are $49.99 synthetic and $44.99 dino

 

[Exproblems]

Nope. Just a smart shopper. Link to coupons...
http://www.pioneerquicklubes.com/coupons.htm
reg prices are $49.99 synthetic and $44.99 dino

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I'm a smart shopper as well and you can find $5 off coupons for oil change shops right in the "Yellow Pages" phone book coupon section, but having said that, it would have still cost me $95 for a rear diff fluid change here had I let them do it.

 

[Exproblems]

Nope. Just a smart shopper. Link to coupons...
http://www.pioneerquicklubes.com/coupons.htm
reg prices are $49.99 synthetic and $44.99 dino

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You really do live in the "discount state"! To satisfy my curiosity on the price differences between shops in our areas, I just phoned one of the Pennzoil shops in Michigan. The guy who answered there said $44.99 for the full synthetic rear diff change and said he could take another $5 off that price for me, or $39.99. I didn't ask about using Royal Purple or what type of synthetic gear oil they would use. I then called a Valvoline (1-716-822-8227) oil change shop near me in Buffalo, NY as a double check on my previous quote, used my vehicle for the quote, he said the price is $99.99 for a synthetic gear oil diff change, no specific brand mentioned. Both our price quotes are correct for our areas. I can't believe there is that much off a price difference for services that are the same, just different states and different National brand Oil change shops. When I first got the price quote several months ago on the rear diff change, I couldn't believe it would cost that much, then the guy said it was because it needed full synthetic oil which is more expensive than conventional gear oil which is true. I know prices can vary state to state, but I didn't think they could vary that much, over 50% difference in price.

 

[GonePostal]

would it be okay to use a synthetic blend oil?