Rear Diff Fluid

[ctrlraven]

Besides going with Royal Purple and Motorcraft with friction modifier which other brands that come in 75w-140 have the friction modifier already in it?

I had to go to 3 different Pep Boys to get 5 qts of RP and don't want to have to chase the stuff down around cause since my 4.10s weren't installed due to needed a new diff I'll have to get more fluid for when the 4.10s and new diff go in.

Does Valvoline 75w-140 synthetic have friction modifier in it?

[fastblackmerc]

I believe you don't have to add the modifier to any synthetic rear end fluid. It's only the dino-based fluids that need the modifier.

[Phrog_gunner]

I have no clue about the Marauder, but I thought most cars only took about 3 qts of diff fluid. When I worked in the auto parts store people always asked for more until I pointed out that their spec was in pints and the bottles were qts.

[juno]

I thought it was 3 PINTS also. I know 3 quarts sounds like a lot!

[NATEHAWK]

Hey Chris it should take about 2 quarts thats it. If you want Royal Purple you can find it easy at most Napa's.

[rayjay]

I had my trac lock rebuilt at the same time and the Ford friction Modifier came in the kit. I used Royal Purple, 2.5 qts. The guy that installed mine is a Ford Master Tech and Ford instuctor. He stated he always puts in the modifier even with Royal Purple. He said the couple times he didn't there were problems so now he always uses it. My $.02 and I have not one noise from my gears.

[Stranger in the Black Sedan]

My car chatters with 75-140 Redline without the genuine FMS additive. I had to add one bottle of the FMS stuff (like 3.x ounces) to the Redline and then it was smooth. Everyone says the Redline is not supposed to need additive but my car, with a stock, perfectly functioning trac lock, needs the extra additive.

[ctrlraven]

I was just getting 5 quarts to have extra, I also put on the TA Performance diff cover so capacity is increased.


Hey Chris it should take about 2 quarts thats it. If you want Royal Purple you can find it easy at most Napa's.
Well mine took almost little over 4 quarts and was just at the fill drain plug. I'd like to go with RP again but $19 a bottle is retarded. Thanks for the tip on Napa, one by my work and one by my house so if I go with RP again I won't have to go all over the place.

[Vortech347]

Peanut butter works best. The oil penatrates the clutch packs and allows them to act as a locker.

[RF Overlord]

I believe you don't have to add the modifier to any synthetic rear end fluid. It's only the dino-based fluids that need the modifier.Not necessarily true. Motorcraft 75W-140 is synthetic yet still requires FM.

[babbage]

I agree with Ray - it takes about 2.5 quarts. I have a trick flow girdle and it does not increase the fluid capacity that much. My girdle has a fill and drain hole. Just fill it up to the top of the fill hole -- then it's full.

Break in with regular dino oil with the FM for about 500 miles. (AMSOIL says to do this)

I'd suggest using AMSOIL 75w-110 - slightly more power - slight better mileage - FM already in it.
I've used the AMSOIL 75w-110 without the FM never had chatter or issue

[gdmjoe]

babbage ... My girdle has a fill and drain hole. Just fill it up to the top of the fill hole -- then it's full.
Have no experience with the TrickFlow girdle, however, do know that the fill hole on the Ford Racing Performance Parts girdle is MUCH HIGHER than the differential fill hole/plug.

http://www.fordracingparts.com/images/part/full/M4033G1_a.jpg

It's OK to fill using the girdle fill hole, however, remove the differential fill hole plug and when it starts to come-out there, it's full.

[ctrlraven]

Yeah my TA Performance cover is the same thing as the Ford Racing gridle.

[NATEHAWK]

TA makes the girdle covers for Ford. I just wanted it to say Ford Racing so I got the Ford one.

[fastblackmerc]

I agree with Ray - it takes about 2.5 quarts. I have a trick flow girdle and it does not increase the fluid capacity that much. My girdle has a fill and drain hole. Just fill it up to the top of the fill hole -- then it's full.

Break in with regular dino oil with the FM for about 500 miles. (AMSOIL says to do this)

I'd suggest using AMSOIL 75w-110 - slightly more power - slight better mileage - FM already in it.
I've used the AMSOIL 75w-110 without the FM never had chatter or issue

How do you get "slightly more power" out of differential fluid?

[Spectragod]

How do you get "slightly more power" out of differential fluid?

It comes with a window sticker, good for 10HP. :D

[babbage]

How do you get "slightly more power" out of differential fluid?


Eh-heh. AMSOIL is the only company that makes 75w-110 weight gear oild -- which is thinner oil than the 75w-140. Thinner oil is easier to spin gears in than thicker oil - hence the comment "slight" cltraven needs all the power he can get if he's going to run 12's

And again to his original question, YES Amsoil does have the FM already in it and it's a damn good oil...

[babbage]

It comes with a window sticker, good for 10HP. :D

If you write to them they might mail you some stickers...



The new viscosity gear lube grade that fills the gap between the 75W-90 and 75W-140 viscosity gear lubes that most people are accustomed to using. Many used the 75W-140 to obtain extra film protection beyond what the 75W-90 viscosity grade offered for their differentials, but found that they sacrificed fuel economy by doing so. This new viscosity grade, 75W-110, offers a high temperature film protection beyond what a 75W-90 offers, without compromising fuel economy. This new mid-range viscosity grade for gear lubes addresses performance, protection and fuel economy.

[babbage]

Have no experience with the TrickFlow girdle, however, do know that the fill hole on the Ford Racing Performance Parts girdle is MUCH HIGHER than the differential fill hole/plug.

http://www.fordracingparts.com/images/part/full/M4033G1_a.jpg

It's OK to fill using the girdle fill hole, however, remove the differential fill hole plug and when it starts to come-out there, it's full.

Ahh, thanks Joe. Mine is much lower looking. too low?

http://www.mercurymarauder.net/forums/attachment.php?attachmentid=15 467&d=1240108684

Not much of a fill hole if it's too low. Regardless I try to put in 2.5 quart bottles of Amsoil 75w-110.

[rayjay]

For a lousy $4 or free with a trac-lock rebuild kit, the Ford friction modifier is cheap insurance.