I have 15k miles on my 2010 XKR now and a brake fluid change is being recommended. I don't recall any other car I've had recommending this as regular maintenance, although I change it frequently on cars that I track using a high temp DOT4 fluid as it is hydroscopic (absorbs moisture). Not sure if that's necessary with whatever the XKR uses. Any thoughts?

Oh and change pollen filter. I can count on one hand the number of times I've driven it with the roof up so I should probably already be dead of pollen and dirt exposure!

Bruce

 

Jag uses DOT4 fluid as factory fill.

This topic has been debated multiple times. I believe Jaguar is being overly conservative in their recommendation. The 2 year interval has been industry since the bad old days when master cylinders were vented directly to the atmosphere as opposed to modern units that isolate the fluid with a diaphragm.

If the cap is never removed (no need to) I fail to see how air can enter...........

 

My mechanic hasn't suggested changing the brake fluid and he's into keep his client cars in top order (at least offering what should be done).

 

Does any of what Goss says still apply?

You should try one of those brake fluid test strips.

 

Ouch. Test the fluid several times a year? Each time the cap is removed moisture-laden air is allowed in. Bad idea.

'Super DOT4? Show me the spec. Hint: there is none. It's a marketing scheme.

I've lost respect for Pat Goss over the years. A lot of his thinking is as old as the car on the right.

 

You'd think that it's a whole bunch of hogwash, but I've had a couple cars now where brake calipers seized up internally (not on the caliper slider pins, but the actual brake pistons themselves) and I believe it was due to never changing the brake fluid, which allowed moisture to build up. Those cars weren't that old at the time either--probably around 10 years.

 

Specs for Castrol Response (Super DOT4):

 

Huh, Castrol Response, you say? I'll have to look the stuff up next time a change is necessary. Thanks for the stats, looks like it's worth it if I can find it.

 

Here's the link to the full PDF:

http://www.castrol.com/liveassets/bp...uper_DOT_4.pdf

 

That's the tested performance of a given fluid, not a spec. All DOT4 fluids would test out pretty much the same as Castrol, possibly better. The Amsoil DOT4 fluid (no claim of being 'super') boils at 304*. That's much higher than the Castrol 'super' DOT4 that boils at 286*

http://www.amsoil.com/shop/by-produc...g-brake-fluid/

There's no DOT spec called 'Super DOT4' and that's what counts in my book.

 

Thank you for the responses so far.

Bruce

 

You are technically correct--Super DOT4 appears to be a marketing thing. But presumably "Super" DOT4 fluids exceed the requirements of the DOT4 specs, so maybe they're still worth something!

Of course, as you point out, many DOT4 fluids already exceed the requirements...

 

My Corvette Z06 has NO specified brake fluid change ... nada, zilch.

Now, the racing brake fluid that I use for track days requires change intervals every few months or so. It has a higher melting point and the side effect is it absorbs water much more easily than the stock GM fluid.

I'd replace the Jag fluid with something else, personally. It isn't hard to do and just takes about 1.5 hours in my garage.

 

Just cause I'm bored and SWMBO has seized control of the TV remote, I've looked up quite a few manufacturer's test results for regular 'DOT4'. All of them far exceed the DOT requirements and most are within a few degrees of Castrol Super DOT4 either higher or lower. I can find no trend that indicates a consistant higher boiling point for the few 'super' DOT4 fluids on the market.

Shell even makes an DOT4 ULTRA.

www.epc.shell.com/.../GPCDOC_GTDS_Shell_Brake_and_Clutch_Fluid


Does Ultra trump Super?

 

I can think of very few car manufacturers that do not recommend brake fluid changes at a minimum of every 2 years.
The only example I can possibly think of might be the more high performance cars using DOT5 (Full synthetic) brake fluids.

As Bruce points out, DOT4 easily absorbs moisture contamination regardless of whether you remove the cap or not. Those of us with track time have learned this lesson with some serious pucker factor.

Vince

 

Skip to 5:30 if you think it's OK to keep using your stock DOT4 brake fluid without changing it ever!

 

Asa the chart says, Castrol Super DOT 4 has a dry boiling point of 286* F which is not high enough for track duty IMHO but great for everyday use. I use Castrol SRF (very expensive) with a dry boiling point of 310* C or 590* F in my Vette for track days. Castrol recommends changing this high performance fluid every 18 months due to its affinity for moisture. But a normal brake fluid should go many years without absorbing enough moisture to worry about.

That video of the Caddy is dramatic ... however, a driver usually starts getting a soft pedal warning before it gets really bad fade so maybe the driver wasn't "listening" to his brakes.

 

That's degrees C in the chart, not F.

The Caddy in the video is a 2012 model and the video was filmed in 2012, so the fluid is not 'old' or the cause of fade due to moisture ingress..

 

Every manufacture of cars has a brake fluid change interval of 2-yrs. Jag, BMW, Land Rover, Audi, Chevy, Ford, VW, on and on and on. Due to climate changes not lid off master cylinder. With the changes in heat and cold cycles thru the year moisture condenses on inside of lines and calipers, just as a fuel tank. Fluid itself has a heat cycle that reduces fluid consistency. Just as oil can absorb just so much dirt. Besides, brake fluid stops the car, think about how many times you press the pedal, and don't realize that sometime you will really need it to save your life.

 

Where does this moisture come from? It's not in the fluid to start with, the system is not vented to atmosphere, the seals don't leak fluid out and let moisture in..............

Gas tanks are a different matter. Water might be in the gas to start with, more can enter every time the cap is removed and there's a huge air space above the fuel level if the car has an almost empty tank.