Changing fluids
 

I'm up for an oil change.

Should any other fluids be replaced at the same time? I know AT oil was replaced in december, brake fluid some weeks ago (I assume they changed or checked when they replaced the brakes), but how about differential oil?

Any recommendations for grades/ products I should use for the various reservoirs?

Re: Changing fluids
 

See my signature line.

Re: Changing fluids
 

Yes sir! Any suggestion on differential oil?

Re: Changing fluids
 

Don't assume they changed the fluid and flushed the entire system and replaced it with new fluid. They may have just replaced the worn pads and topped off the system at the reservoir.

If they replaced a brake caliper, they would have bled and flushed the system. Check your receipt or ask the shop.

Brake fluid should be changed about every 2 years. If you are not sure when it was done, it's better to replace it.


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Re: Changing fluids
 

The gear oil goes in the front and rear differentials.

Re: Changing fluids
 

Tony, what do you think about AmsOil DOT4 brake fluid?
I believe that I am going to put it in the cars I care about.

Re: Changing fluids
 

I am not a fan in flushing the ATF. Both times it was done on my SVX, my Trans failed. Coincidence?:confused:

Re: Changing fluids
 

It depends on how the transmission is flushed.
When the local Subaru garage started using a pressure flush machine, powered by the approximately 100 psi air line, the failure rate was about 50%, AND JUST A COINCIDENCE!:rolleyes:
However I see no problems with usind a drain and fill system,
a gravity system,
or a system like BG Products, that uses the internal transmission pump.

Re: Changing fluids
 

I usually have my transmission flushed every 25,000 miles by my Subaru dealership, which has the machine that uses the SVX's own internal pump to transfer the fluid. It takes about 14 qts. to assure that all the old fluid has been pumped out.

Still shifting flawlessly after 14 years at 135,000 miles :)


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Re: Changing fluids
 

I haven't looked into brake fluid much. Amsoil makes decent stuff like Mobil 1 does and BG does. With brake fluid, I would think heat transfer and heat capacity would be the most important along with coefficient of expansion and water solubility. I just don't know how the good guys stack up against each other in brake fluids. The first place I would go to research it is bobistheoilguy.com. They even have a decent search engine. I would bet Amsoil, Redline and like minded companies would all have good products.

Re: Changing fluids
 

Because I love you Tom:

DRY:580F -- WET:410F -- $/qt~$36.27 -- AMSOIL SERIES 600
DRY:590F -- WET:410F -- $/qt~$39.67 -- AP RACING 600
DRY:593F -- WET:420F -- $/qt~$27.99 -- MOTUL RBF600
DRY:610F -- WET:421F -- $/qt~$49.98 -- NEO SUPER DOT 610
DRY:620F -- WET:425F -- $/qt~$??.?? -- COBALT SUPER XRF
DRY:590F -- WET:518F -- $/qt~$60.58 -- CASTROL SRF

These are the "best of the best" brake fluids. I sorted them by wet boiling point. This is what matters after 2ish years of use when the fluid has absorbed some water. What is hard to find is thermal conductivity, heat capacity, water solubility and thermal coefficient of expansion. Most supplier only list dry and wet boiling point. However, I know Motul and Amsoil are fully aware of the benefits of esters in terms of being able to remove heat from metal surfaces.

I would say the Castrol is the best but the Motul might be the best buy of the bunch. I would go with the Motul over the Amsoil. Look on Amazon for it.

In contrast, Valvoline (a popular, easy to find, inexpensive choice) has a dry boiling point of 480F and a wet boiling point of 311F.

Re: Changing fluids
 

Sadly the SVX brakes aren't capable of exceeding the temps of the valvoline syth. fluid as Dave and I sheared a rear caliper on the racer without exceeding the dry fluid temps on the racer years ago. IMHO anything beyond the cheap stuff changed a couple times a year for race situations is like pissing in a toilet... Nothing but a waste of dead presidents:lol:

Re: Changing fluids
 

As with most modern transmission flush machines, they do not use pressure at all. They use the transmission's own pump to transferin the new fluid that displaces the old fluid, which is collected and thrown away.

There are two basic types of flush machines. Here is how they work and the differences between them.


COOLER LINE FLUSH MACHINE:

This type of flush machine connects into the transmission cooler lines. BG makes this kind and here is how it works.

The line going from the transmission to the transmission cooler is disconnected and connected to the machine line IN. The line OUT from the machine, carrying new fluid is connected to the line going to the cooler. There is a chamber on the machine that has a diaphragm in it. The top part of the chamber above the diaphragm is filled with new ATF

The engine is started, which turns the torque converter and the input shaft on the transmission. The input shaft turns the transmission pump and it makes hydraulic pressure. This causes the ATF to flow through the cooler line. As fluid leaves the cooler line, it enters the chamber on the flush machine. As the old fluid side of the diaphragm fills it pushes the diaphragm up and forces new fresh fluid into the transmission.

After a while the old fluid is collected in the machine and it is replaced by new fluid. Now the transmission has been flushed, really pretty simple, and you can see the machine caused no pressure and all fluid transfer is done by the transmission's own pump.


The main thing I do not like about this type of flush is that they sell the supposed benefit that they do not have to drop the pan and change the filter (like that is a benefit) Dropping the pan is very important. Looking in the pan is a fantastic diagnostic tool that can tell you if something is going wrong in your transmission.



PUMP INLET FLUSH MACHINE:

This is the type of flush machine my Subaru dealer uses. It connects to the pump intake after the pan and filter are removed. This machine only supplies fresh new fluid to the pump intake and, as the fluid passes through the transmission, it dumps out to a collection tray and never goes back through for a second pass. All of the old ATF and crud are GONE and replaced with fresh new fluid. After the service a new filter is installed, the pan replaced and then it is topped off with new fluid to the proper level on the dipstick.

This process takes a total of 14-15 quarts of fluid to flush out 12 quarts of old fluid, replaces all of the fluid, and gives the mechanic the opportunity to look in the pan for anything unusual that would indicate a pending failure.

This type a flush does take more effort to do and makes a little more of a mess. It costs a little more also, but I think it is worth it.

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Re: Changing fluids
 

And as for brake fluid, I have been using the ATE Super Blue Racing Fluid for years.

DOT 4
Dry boiling point: 536F
Wet boiling point: 388F

It is a blue color and I alternate every other fluid change with the ATE TYP 200, which has the same specs. This fluid is amber in color so it is easy to see when all the old fluid is drained because of the color change.

About $17.00 per liter.
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Re: Changing fluids
 

Ben, I have been using Valvoline fully synthetic for years,
but recently read of the higher boiling point os AmsOil,
and was intriuged.