I am going to change all the fluids on my new 2007 F150 5.4L 4X4.
What do you all recommend using?
Tranny, just a on my lift filter and what ever fluid comes out or take it for a total flush?
rear end, Royal purple?
Thank you.
Bill

 

Personally I much prefer a pan drop and filter change for a transmission service. Some places want to run a cleaner through with the flush and I just don't trust that. A straight fluid exchange flush would be all right as far as I'm concerned though. I'm not too picky when it comes to transmission fluid. Anything I have had that took Dex3/Mercon always got Supertech and I never had any issues. I get Motorcraft MerconV out of bulk so that's what I use now. If you have a limited slip the Royal Purple is great because it already has the friction modifier in it. I believe Mobil 1 does as well. Just use a full synthetic 75w140 and use the modifier if you have limited slip and it's not included in the fluid. If you change the fluid in the transfer case it takes Dex3/Mercon or motorcraft transfer case fluid not MerconV. I have heard the additives in the 5 are not ideal for a transfer case not sure if that's true but why risk it.

 

thanks, how do I know if it is a limited slip? the tags on the rear are hard to read, is there different way to find out? both wheels spin on ice in my driveway but when I have it on my lift and spin one wheel the other one turns the other direction.

 

You can post the axle code from the door jam here and I'm sure someone would be able to decode it for you. I can't remember them all anymore but I wanna say 2 numbers were open a number with a letter was limited slip.If you look at the tag on the rear diff one should have your ratio and an L if it is limited slip. Such as 3 73 or 3L73 3 55 or 3L55.

 

Here it is.

 

Axle code 19 is 3.55 conventional. So no limited slip. If I remember correctly.

 

I wonder how much and how hard it would be to make it one.
Now I just have to figure out why I am only getting 10-10.5 MPG.

thanks for your help!

 

Any recommendations on what to put in the rear??

 

Hi for the rearend can use any fluid with right rating. I have limited slip and changed my rearend and front axle to royal purple and my milage improved. Also changed transfer case to royal purple. This changing of fluids should help your milage, my rearend fluid was pretty bad and i only had half the miles of the recomended change interval, I was stuck once in some mud so not sure if that caused the fluid to look so bad.

Hope this helps you .

 

If you have an advance auto parts they often run online promo's that you could use to save a good amount of money. If that's an option for you I would look into the Royal Purple or Mobil 1. I have used the Royal Purple with good results and going on reputation alone would trust the Mobil 1. I'm not a Mobil 1 user but I can recognize that you don't stay number one in synthetic lubricant sales as long as they have been by putting out junk products.