How often for brake fluid change, mine last changed approx 11,000 miles ago after new discs were fitted all round. This was approx 2 years ago. Judging by the discs it has not been driven hard as hardly any wear. Is my independent tech just touting for work. He has been a great guy to deal with during previous ownership of XJ so I have faith in him. Very helpful guy. Former Jaguar trained tech.

 

The period is described in the service manual... but as you state, the car is rarely used. Seems pretty cut and dry to me.

 

well fluid life and disc life are not too closely correlated. heat cycling that would not be apparent from looking at the discs still does break the fluid down, but 11k with light driving really does not sound like it should be that bad yet.

you can pop the cap off the reservoir and take a look at it, check google images for "bad brake fluid" there's plenty of examples. light brown with flakes in it is your warning sign that it needs doing soon. if it looks really awful, there's probably something wrong with the reservoir or master cylinder, probably bad seals.

 

Open a bottle of new brake fluid and look at it. Then open your cars brake fluid cap. if you ar using clear fluid it should be clear. If you are using a colored fluid they both should look a like and be clear. Any discoloration means water absorption. Change it.

 

Thanks guys, appreciate all advice.

 

Andy - I drive my 2006 XK around the same average miles/year as you. I changed brake fluid last weekend, three years since the prior change. The fluid coming out of the wheel cylinders was moderately dark compared to new brake fluid. I use the ATE SL6 DOT4 fluid which has a slight amber color when new.

 

Although the recommended interval is 2 years, I think this is more a case of JLR finding something to include in the maintence schedules rather than genuinely having any technical or scientific justification.

However, with a trusted independent, I'd be very tempted take the "suggestion" and keep him on side. You will almost certainly get more than the cost back in future goodwill and non-charged small items.

Graham

 

actually there's also piping through the ABS unit i failed to mention which we have on the newer 5.0's and which you may have too, not sure. i think these are hard lines, but there may be a way for moisture to get into the fluid through that unit, i don't know. if you take it for a second opinion, you know, just tell them a tech suggested a brake fluid flush, not that some dummy on the internet told you that your master cylinder seals might have gone bad.

 

Here's a cheap DIY kit to test for moisture in your brake fluid
https://www.ebay.com/itm/Brake-Oil-F...8AAOSw5sBbhRxL

If the fluid is dirty compared to new, I change it
If there's any moisture in the fluid, I change it
If it's been more that 2 years, I change it (that's not just a Jag recommendation)

 

When I changed to my Wortec discs in 2018 my Indy did a brake fluid flush and refill, in 2019 and 2020 they did hydrometer (?) checks. Year 1 if was 0.5% water year 2 = 0.9%

They've advised me not to change until it goes above 2%

On-line resources recommend changing at 3% so my Indy is erring on the side of caution, but based on the increase thus far, I'll be fine for about 4yrs.

Easiest thing is to get yourself a tester (around £10 or 15 usd) and check it yourself, as there's no point changing it unless you actually need to.

Not sure why any other poster has said this so far?