'08 Mustang GT question

[andrewg]

Hello all....I've got a question or two about the factory fliuds in my Mustang. I want to make this car last a very long time. Keeping that in mind can any of you tell me what I should do about my power steering, rear axle, and transmission fluids? Ford says the axle has already got a synthetic 75w-140 in it, so I assume no change to Mobil 1 or Redline is needed...correct? What about the transmission then? It's got Mercon V in it now but I was thinking about using Amsoil ATF or similar synthetic. Is this difficult for me to change or should I take it (with fluids in hand) to a shop? Funny thing is that there is NO dipstick. And what about the power steering? Is it any difference using a synthetic fluid for that? I know it would use an ATF like the transmission.
Thanks for any advice...even if it's just to stick with conventional fluids and the factory schedule.

 

[Bulli]

since the car is new i would change all the fluid out sooner.
change engine oil at around 3000 and baby the car. If you don't baby it change it out sooner IMO.
I would change the transmission fluid with the same fluid that is in the car at around 15k and do a couple drain and refills so by the 30k mark its about 90% new fluid.


Basically since the car is new and under warranty i would use recommended fluids and then after it's up use anything you want.

 

[scudpilot]

Originally Posted By: andrewg
Hello all....I've got a question or two about the factory fliuds in my Mustang. I want to make this car last a very long time. Keeping that in mind can any of you tell me what I should do about my power steering, rear axle, and transmission fluids? Ford says the axle has already got a synthetic 75w-140 in it, so I assume no change to Mobil 1 or Redline is needed...correct? What about the transmission then? It's got Mercon V in it now but I was thinking about using Amsoil ATF or similar synthetic. Is this difficult for me to change or should I take it (with fluids in hand) to a shop? Funny thing is that there is NO dipstick. And what about the power steering? Is it any difference using a synthetic fluid for that? I know it would use an ATF like the transmission.
Thanks for any advice...even if it's just to stick with conventional fluids and the factory schedule.

I believe the most overlooked fluid is the rear differential oil.
At 5,000 miles I would drain it and refill with Ford OEM or Amsoil Severe Gear 75W140. Those gears throw out a lot of metal as they are breaking in.

 

[c3po]

I changed out the Differential Fluid at 10,000 miles after I picked up a 2004 Mercury Marauder in December 2006, it looked nasty, it had a greyish look too the fluid.

That greyish color was probably the break in metals. I would definetly change out that Diff Fluid at 5000 miles.

 

[andrewg]

Thanks guys....I won't mess with the transmission then until a year or so. I'll take it to the dealer (I sort of trust them) and have them clean out the filter(s) and refill with OEM fluid. And I'll wait 5k or so and suck out/refill the rear end with a quality synthetic.
Does the power steering fluid have enough stress to benefit the use of a synthetic over time?

 

[Bulli]

well as power steering fluid goes i think if you just keep new fluid in there even if it is dino it will be better then keeping a synthetic in their longer.

The fluid was nasty in my ford escort and the pump was having a hard time during cold weather. After just using Ford MErcon V ATF/ PSF it works great again.

I heard you have to change PSF when you change your coolant, but IMO every 2-3 years seems just about right.

My moms 96 cavalier didnt have its changed 12 years or so and it was still pretty clear. And yea my 02 escort was black!!!

So just watch the fluid and make sure its clear or light amber.

 

[LAGA]

In my 05 Mustang GT. I changed out the rear end fluid at 5k with Amsoil 75w-140, I used the limited slip additive also. The trans is somewhat sealed on that car. There is a fill plug on the side but it is hard to get at. There is a special procedure to drain and fill the trans so it is not a do-it-yourselfer. Ford says the Mercon V fluid should be good for 100k, I will change mine at 50k. The PS uses Mercon V also. I changed the reservoir out at 20k with Amsoil ATF. The car runs great for me.

 

[mechtech2]

I would consider flushing out the differential with fresh fluid in a year or so. Simply because of particulate matter from break in wear and possibly from factory machining remnants. Also any clutch pack material.
I like doing a turkey basket flush of the PS and brake fluid reservoir. Just suck out the old, and refill. No mess, no fuss, and it keeps fresh fluid in there. Once or twice a year should be good.
Every two years for a trans pan fluid change for the auto trans should suffice.
Motorcraft fluids are very good. Always a good choice. Amsoil and Redline are wonderful , but make sure you get the right grade because they have a number of offerings.

 

[Jason2007]

I have an 07 GT and I changed the rear end lube at 12k and filled it with Royal Purple 75w140. It already has the positive traction additive in it. Rear end is a quiet as a mouse and works perfectly.

 

[Barkleymut]

Good thread as I have been wondering about my 07 GT with 21K on it. I have a 5spd manual and I drained and refilled the manual trans about a month ago. It was super easy to drain the old fluid, getting the new fluid in was pretty difficult. Just finding and removing the bolt was tough. I used Castrol MerconV to refill, I will do it again at 50K. As for the coolant, I will do it once the weather warms up in March. I did my first oil change at 900 miles and another at 3K. Ever since it has been between 4-5K with MC semi syn 5-20. I plan to drain and refill the rear diff in march also. As for the PS I will probably wait till the car is 3 years old. Brake fluid probably the same. I generally just try to find whatever fluids the manual recommends and then find it at autozone or advance auto on the weekend I plan to take on the work.

 

[andrewg]

Great replies folks! I will review what everybody has said here and replace most of my fluids in the spring. I was hoping to be able to do most of the work myself but from what I understand many drain/refill points are a real b***h to get to. I've only got a few thousand on the car now and because of our recent snow I haven't driven it for over three weeks.
Next summer I may drive it across the U.S and back so I want to change out with fresh fluids before then. (Yes, I am rather anal...but that's kind of the nature of this site anyway, right?)

 

[Jason2007]

I put Royal Purple Synchromax in my 07 GT 5-speed and the shifts are much smoother than when it had MercV.

 

[OVERKILL]

The 8.8 is a VERY strong rear-end. My Townie still has the original fluid in it

Changed out the original fluid in the Mustang when I bought it, had over 200,000 on it at that point.

M1/Amsoil/RP ATF works fantastic as PSF for a Ford.

Same goes for the transmission.

 

[Buffman]

^^ Correction Should be Made. That in stock form it wasn't a Very Strong Rear end, till they started using 30+ spline axles in them. (I tink the stangs now use 31 spline). Mustang article few years back discussing rear ends, and the 8.8 is very nice, but it still has the downfall the 7.5" does: the 28 spline axles.

You want a really strong stock rear end, the 8.5" 10 bolt from GM with 30 spline axles

 

[OVERKILL]

Originally Posted By: Buffman
^^ Correction Should be Made. That in stock form it wasn't a Very Strong Rear end, till they started using 30+ spline axles in them. (I tink the stangs now use 31 spline). Mustang article few years back discussing rear ends, and the 8.8 is very nice, but it still has the downfall the 7.5" does: the 28 spline axles.

You want a really strong stock rear end, the 8.5" 10 bolt from GM with 30 spline axles


The ring and pinion setup were always strong. Logically, if you are upgrading the car substantially beyond stock, you want to install the 31-spline axles. It's a common upgrade and inexpensive.

That being said, I know of a number of cars making ~400RWHP with the stock 28-spline axles and not breaking them. That's a dead-hook launch on a slick at the track.

The 7.5 is FAR weaker than the 8.8. I've personally witnessed a STOCK 86 walk an axle at the track on STREET TIRES.

A good friend of mine's dad's S10 had a 7.5, which bent both axle tubes on a tire behind a built smallblock.

Truck now has an 8.8 (31-spline, huge tubes) out of an Explorer in it.

I know I know, Ford parts in a Chevy. Scary.....

 

[artificialist]

Some people go 250K miles without ever changing their gear oil, others have problems after 50,000 miles, even with synthetic oils.

Changing the factory fill at 12,000 miles is cheap protection.

Just be prepared to pay around $15 per quart for 75w140 synthetic gear oil.