Euro Cars - Diff Oil Change Advice / Experiences.

[WD Pro]

Just thought I would post my experiences for those of you with a Euro (or any Track Lock diff) car and want to change the diff oil

It's a bit of a long story, so bear with me ... lol.

In bullet point format :

• I broke a diff bolt.
• Ford took care of the warranty.
• Part of the job was to replace the diff oil.
• Part of the job was also to include fitment of the steeda diff bushes and cradle lock out.

I got the car back and I have to say it was great, much more 'solid' feeling at the back and much more predictable during enthusiastic driving, BUT I had a couple of small issues (although they were far outweighed by the improvements) :

• Full lock turns on a cold diff = huge diff chatter (like the diffs going to drop out or explode kind of loud ).
• Some very marginal gear whine, only when warm and only when on / off throttle at low speeds in first gear (7 to 11 mph driving over speed humps etc). Can't hear it when the speed is faster due to other road noises and it was kind of mild enough where my misses would be like 'what noise ?' lol.

So it would have been dead easy to blame it on the Steeda kit, but as it also drove diffetly I part convinced myself the diff was acting differently, which made me look closer at the diff and the oil change, this is the bit that's especially important on a euro

So UK manual (no friction modifier) :

USDM manual (with friction modifier) :

So a call to my tech confirmed no friction modifier, no mention of it on their system.

So I get the friction modifier spec and part number and go visit the parts department = They recognised the number, but couldn't order it and confirmed it was obsolete and removed from the system several years ago. I think he said the last cost was circa £45

So I bought some of ebay (£13 delivered ) along with some big syringes from Amazon and spent a bit of time under the car :

Sucked 130ml out, squirted in the friction modifier, squirted oil back in to bring the volume back to where I started (I will check it again when cold / level) :

I immediately did a full lock turn in the street, the chatter was significantly reduced.

Took it for a drive with a few roundabouts (and a few wiggles on exiting them lol) then parked it up overnight.

Cold start the following morning, full lock coming off the drive (where I initially noticed the noise) and it was silent.

Got it warm (but not stinking hot) and it was silent over the speed humps coming home.

So in my experience, on my car and its current setup, friction modifier is definitely needed if you want a quiet ride. 'Maybe' you would get away without it on a totally standard car / fully rubber bushed / partially worn diff ?

Interestingly, I had semi convinced myself that some the the nicer driving properties were due to the diff locking up quicker due to the lack of friction modifier and I was worried I would miss that by adding the modifier back in, but as it turns out it's still driving the same so the differences must be due to the steeda kit

@tj@steeda @SteedaTech - I thought you might be interested in the above for two reasons :

1. It would have been easy to blame my initial noises after the rebuild on your kit, where in truth it was the oil spec that made the difference on my car.
2. It's a nice compliment towards your kit that locking the subframe and diff out can make such a noticeable difference to the back end feel on these cars

WD

Sponsored

 

[tj@steeda]

Wow - thank you for the write-up & feedback. It is truly appreciated.

Best Regards,

Tj

 

[WD Pro]

My oil was free, Ford put it in for me and the friction modifier wasn’t hard to find …

WD

 

[Nightmonkey]

@WD Pro
Your car is definitely way too clean from underneath!
You should drive it!

 

[ice445]

Yeah, given how sensitive these diffs are to not having enough modifier, its surprising the manual doesn't list it. Probably an oversight though.

 

[LDHunter]

Wow! Thanks for the info....
Genuine Ford Fluid XL-3 Friction Modifier Additive - 4 oz.
is a whopping $7.87 delivered here in the USA from Amazon.

 

[Esset]

I'm currently dealing with a similar issue – the differential fluid change. Just like you, I found in the EU manual that I need oil according to the WSS-M2C942-A specification, but without any friction modifier. However, according to the US manual, a friction modifier is required.


I ordered oil that meets the spec – RAVENOL DGL SAE 75W-85 GL-5 LS – which already contains a friction modifier for limited-slip differentials. Now I’m unsure whether I should still add an extra friction modifier as per the US instructions?


The US manual specifically mentions Motorcraft® SAE 75W-85 Premium Synthetic Hypoid Gear Lubricant, which is also formulated for LS diffs, yet it still says to add a friction modifier.

Any thoughts?

 

[Nightmonkey]

Try without, if not good for you, add some XL-3.

 

[robvas]

I ordered oil that meets the spec – RAVENOL DGL SAE 75W-85 GL-5 LS – which already contains a friction modifier for limited-slip differentials. Now I’m unsure whether I should still add an extra friction modifier as per the US instructions?

No, you don't need to add it if the gear lube already has it in it.

 

[Nightmonkey]

No, you don't need to add it if the gear lube already has it in it.

In theory I would agree.
In practice, the Ravenol oil gives a better grip for the LS clutch depending on the temperature, which means that the rear axle is a bit bulky immediately after driving off.
I'm still thinking about if I should add some XL-3, but over all I like the behavior when it is warm.

Sponsored