Royal Purple in Fusion AWD Rear Diff?

[MadMerc]

Ford recommends 80w/90 gear oil for the rear diff in my 2009 Ford Fusion AWD. I was thinking about switching to a synthetic 70w/90, like Royal Purple, to help free up a little more MPGs due to less drag.
Would Royal Purple be compatible, or should I just go with the same old weight and type?
Thanks in advance!

 

[gathermewool]

What's the required spec? It's probably an open diff, so, so long as it's GL-5, it may not matter one iota which gear lube you use.

You most likely won't notice any difference at all, so far as mileage is concerned.

 

[Clevy]

I like RP fluids. I used their gear oil in my Harley's 6 speed. It was better than the syn 3 Harley specifies however if found the best gear oil I've ever used was red line.
RP is great but I found in my Harley redline was better.
Just before I totalled my ram I changed the front pumpkin and rear diff using red line and I can say without a doubt the truck felt like it rolled easier.
I lived in that truck. I noticed everything about how it ran,drove and handled. My butt dyno is very accurate in my daily drivers and the gear oil change made a noticeable difference.
However the original fluid looked as though it was never changed since new so that could be a reason why it felt like it rolled easier.
You can't loose with RP though. If I cannot attain redline RP is my next choice.
I've never used Amsoil severe gear but I've got 2 friends who run it in their track mustangs and hey swear by it.
If you use redline shockproof you don't need to add friction modifier,I don't think its required with RP either but my friends do add it to the severe gear,whether its required or not I cannot say with certainty.

 

[dparm]

An 80w90 and 75w90 are effectively the same viscosity once warmed up, so the differences you see will be negligible.

That being said, the RP 75w90 gear oils are decent.

 

[chevrofreak]

It takes a while for a differential to warm up, and even at 100F a typical 75w-90 is half as thick as an 80w-90.

I switched my 2006 Mercury Mariner Hybrid rear differential to Red Line 75w-90 and the center differential to 75w-140. I had to have the center differential replaced to the tune of $1280 last year, so I am trying to protect my investment. My tank averages seem to be a bit higher.

 

[NHHEMI]

Originally Posted By: MadMerc
Ford recommends 80w/90 gear oil for the rear diff in my 2009 Ford Fusion AWD. I was thinking about switching to a synthetic 70w/90, like Royal Purple, to help free up a little more MPGs due to less drag.
Would Royal Purple be compatible, or should I just go with the same old weight and type?
Thanks in advance!


As long as there is no specific wording about not using synthetic gear oil go for it. RP MaxGear is great stuff.

My 4WD Jeep Patriot calls for GL-5 80W90 in the PTU and RDA. I would run RP MaxGear 75W90 in both without pause EXCEPT Chrysler specifically adds ""non synthetic" after the GL-5 80W90 in the owner's manual. I ended up using Kendall 80W90 conventional when I serviced the two units.

So unless you have a similar warning I would run the RP.

 

[MadMerc]

Originally Posted By: chevrofreak
It takes a while for a differential to warm up, and even at 100F a typical 75w-90 is half as thick as an 80w-90.

I switched my 2006 Mercury Mariner Hybrid rear differential to Red Line 75w-90 and the center differential to 75w-140. I had to have the center differential replaced to the tune of $1280 last year, so I am trying to protect my investment. My tank averages seem to be a bit higher.


Since the AWD systems are the same for the Fusion and your Mariner, I'm going to give it a try. Ford recomends SAE 80W/90, so I think that I'll be ok with the RP.
Thanks for the responses, guys! I appreciate it!

 

[tudorart]

Red Line Shockproof DOES NOT contain sufficient friction modifier for a limited slip differential in street use.

What you read on the bottle is for racing use and faster lock up. Parking maneuvers and tight turns require a bit more for perfectly smooth operation.

RL has better products for street use.

 

[gathermewool]

Originally Posted By: tudorart
Red Line Shockproof DOES NOT contain sufficient friction modifier for a limited slip differential in street use.

What you read on the bottle is for racing use and faster lock up. Parking maneuvers and tight turns require a bit more for perfectly smooth operation.

RL has better products for street use.



His AWD Fusion DOES NOT contain an LSD, nor does it require any sort of special lubricant, IMO.

 

[chevrofreak]

Originally Posted By: MadMerc
Originally Posted By: chevrofreak
It takes a while for a differential to warm up, and even at 100F a typical 75w-90 is half as thick as an 80w-90.

I switched my 2006 Mercury Mariner Hybrid rear differential to Red Line 75w-90 and the center differential to 75w-140. I had to have the center differential replaced to the tune of $1280 last year, so I am trying to protect my investment. My tank averages seem to be a bit higher.


Since the AWD systems are the same for the Fusion and your Mariner, I'm going to give it a try. Ford recomends SAE 80W/90, so I think that I'll be ok with the RP.
Thanks for the responses, guys! I appreciate it!

I had originally switched to Amsoil Severe Gear 75w-90, but I have some minor seal leakage on my rear differential, so I wanted some ester based stuff to hopefully keep the seals pliable. Both have done well in it.

My replacement PTU does not have a drain plug like my original did. My dads 2008 Fusion doesn't have a drain plug on the PTU either. I was still able to use a small diameter steel tube to suck out almost every drop of fluid and replace it in my Mariner. These things are notorious for boiling gear oil and damaging the seals. So far so good with the Red Line 75w-140. You might consider trying this also.

 

[chevrofreak]

Also, I am pretty certain that the owners manual in my dads 2008 Fusion specifies 75w-90 for the rear differential, and that it is a lifetime fill.

 

[chevrofreak]

Never mind, I downloaded a manual and it does say 80w-90. Looks like I will be doing both differentials on my dads car.

 

[hypervish]

Originally Posted By: Clevy
I like RP fluids. I used their gear oil in my Harley's 6 speed. It was better than the syn 3 Harley specifies however if found the best gear oil I've ever used was red line.
RP is great but I found in my Harley redline was better.
Just before I totalled my ram I changed the front pumpkin and rear diff using red line and I can say without a doubt the truck felt like it rolled easier.
I lived in that truck. I noticed everything about how it ran,drove and handled. My butt dyno is very accurate in my daily drivers and the gear oil change made a noticeable difference.
However the original fluid looked as though it was never changed since new so that could be a reason why it felt like it rolled easier.
You can't loose with RP though. If I cannot attain redline RP is my next choice.
I've never used Amsoil severe gear but I've got 2 friends who run it in their track mustangs and hey swear by it.
If you use redline shockproof you don't need to add friction modifier,I don't think its required with RP either but my friends do add it to the severe gear,whether its required or not I cannot say with certainty.


I had the complete opposite experience in my RX.

The Royal Purple makes the car feel like it rolls much better. I put in RP 75W-90. The Redline that was in it had only about 52k miles on it. So it shouldn't have been worn out. However, I don't remember what weight it was. So maybe that's why it rolls easier on RP.

 

[MadMerc]

Originally Posted By: hypervish
Originally Posted By: Clevy
I like RP fluids. I used their gear oil in my Harley's 6 speed. It was better than the syn 3 Harley specifies however if found the best gear oil I've ever used was red line.
RP is great but I found in my Harley redline was better.
Just before I totalled my ram I changed the front pumpkin and rear diff using red line and I can say without a doubt the truck felt like it rolled easier.
I lived in that truck. I noticed everything about how it ran,drove and handled. My butt dyno is very accurate in my daily drivers and the gear oil change made a noticeable difference.
However the original fluid looked as though it was never changed since new so that could be a reason why it felt like it rolled easier.
You can't loose with RP though. If I cannot attain redline RP is my next choice.
I've never used Amsoil severe gear but I've got 2 friends who run it in their track mustangs and hey swear by it.
If you use redline shockproof you don't need to add friction modifier,I don't think its required with RP either but my friends do add it to the severe gear,whether its required or not I cannot say with certainty.


I had the complete opposite experience in my RX.

The Royal Purple makes the car feel like it rolls much better. I put in RP 75W-90. The Redline that was in it had only about 52k miles on it. So it shouldn't have been worn out. However, I don't remember what weight it was. So maybe that's why it rolls easier on RP.


Yeah, that's the feel that I'm after. Thanks for the info!

 

[camelCase]

I'm personally not a fan of RP's gear fluids. They seem to degrade much faster than comparable options on the market. Amsoil's 75w90 gear fluid is great stuff. Used it on my Formula SAE car's rear torsion T1 diff with good results. I use Rockland Standard Gear's transmission fluid in my personal vehicle. If their diff oils are just as good - I'd definitely give them a look. The price is pretty [censored] competitive too.

 

[NHHEMI]

Originally Posted By: camelCase
I'm personally not a fan of RP's gear fluids. They seem to degrade much faster than comparable options on the market.


Never seen that and I have used it in tons of different applications.

 

[dwcopple]

let me know if you do this, i can't figure out how to access the drain and fill on that rear diff. Not with rear up on ramps anyways. You must have to jack it and let it sag somehow?

 

[MadMerc]

Originally Posted By: dwcopple
let me know if you do this, i can't figure out how to access the drain and fill on that rear diff. Not with rear up on ramps anyways. You must have to jack it and let it sag somehow?


I'm going to change the fluid when I install my new rear roll bar. Hopefully it will be easier to do when I have the car up on a lift.

 

[dwcopple]

will look for update then.