PTU and Rear diff fluid type and change

[talldude42]

Hello all. Just purchased a used ford flex ecoboost awd and it needs a tune up and fluid changes. I am about to change the fluid in the PTU and I purchased Royal Purple 75w 140. It was only a dollar more than mobil 1. Anyone happy with that fluid or do you recommend something else?

I also need to change the rear diff fluid. Any recommendations there as well? Do I need to add any friction modifier to it? Thanks in advance for the help!

 

[ZSHO]

I would use the same Royal Purple which is a Great quality gear oil for the Differential!
75W-90 Gear oil with added friction modifiers .

Royal Purple Max Gear 75W90 Synthetic Quart.  $17.19 - With-Promo.
Due setup an Intro @ your earliest convenience,thanks and welcome.  Z

https://m.pepboys.com/product/details/9334458/01519?quantity=1

 

[ajpturbo]

Check the bottles of royal purple and see if they meet the ford specification listed in the manual...simply using the correct viscosity is not enough...the ford spec will start with WS I think

 

[talldude42]

I believe the Royal purple bottles say meets specs for GL-4 and GL-5. I know the PTU needs a fluid that can stand up to the heat from the exhaust as well as the normal wear the gear box puts on the oil.

I was thinking of using schaeffers gear lube. I use their oil in my 7.3l power stroke and have been happy with them. But i think they are more of a "boutique" oils that all of people are not thrilled with using from the testing stand point. Although their test data appears to be better than mobil 1. 

 

[ajpturbo]

I believe the Royal purple bottles say meets specs for GL-4 and GL-5.

Not the same thing....you need to make sure it meets the ford spec...they start with WS

I think GL-x is just a oil classification but I’m not sure

 

[ToMang07]

I'm running Amsoil Severe Gear in mine

Sent from my SM-G960U using Tapatalk

 

[SHOdded]

Try Redline Lightweight Shockproof for BOTH the PTU and the RDU.  Yes, it will work in both applications.  You want ester based fluid for best heat resistance.  But regardless, it is not a set-and-forget situation.  Just like in applications that have OEM drain plugs and service intervals from the factory, these fluids should be changed out on a regular basis.

Since you have a 2014 Flex, I believe the PTU is the cooled variety with a drain plug.  The HOWTO post meant for the SHO PP variant should help you out a bit.
https://www.ecoboostperformanceforum.com/index.php/topic,4951.0.html

 

[talldude42]

I'm running Amsoil Severe Gear in mine

Sent from my SM-G960U using Tapatalk

I emailed royal purple and they said that their max gear oil does meet for specific specs for both the ptu and rear differential but thanks for making me look into it farther. I have no idea when the last time it was done so i think this fluid change will have a short interval life to clean out on gunk that may have formed in the case and go from there.

 

[geophb]

I wouldn't run any sort of friction modifyiers or "limited slip" in the rear diff. Because I would be worried that it might cause slippage in the clutches. Coming from atv world with wet clutches.  PTU shouldnt matter about modifiers, cuz its just a gearbox, it just gets really HOT.

 

[shoNoff]

I used Lucas synthetic 75w-140 in ptu and lucas 75w-90 in rear end. I changed both roughly 2/3 weeks ago and the car feels much smoother. Could be me though lol

 

[talldude42]

I used Lucas synthetic 75w-140 in ptu and lucas 75w-90 in rear end. I changed both roughly 2/3 weeks ago and the car feels much smoother. Could be me though lol

Ive read alot of similar results after changing the fluid out. Hopefully i can get to it tonight after work or in the morning.