Hello all only been owner since December but could anyone tell me how often I should be filling my coolant level as I seem to be doing it every 400 miles or so but no sign of a leak. Also can the coolant be diluted. Thanks

It shouldn't need topping up really. And no, you shouldn't really dilute it.

Mine was losing coolant last year - turned out to be a leak in a thermostat housing I believe. Otherwise the EGRs are common locations for leaks. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Funny enough topped mine up again this morning. I don't do it that often but still interested in what could be the cause ? all systems have been checked & double checked & the coolant is definitely lower  16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

I had a similar issue on a 2005 4.4HSE. The local specialist claimed it was a hose deep in the bowls of the engine, cost me £500 to prove it was actually a simple and known fault with the header tank, which had failed and was only £60 to replace!

One thing I remember was being able to smell coolant under the hood when she was running hot, so it might be worth checking this out on yours.

Best of luck. --------------------------------------------------------
RRS TDV8 Black/Black (Gone)
RRS TDV8 Stornaway (Gone)
RR Vogue TDV8 (Gone)
RRS 4.4V8 (Gone)
Defender 110 300tdi (Stolen, much missed)
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LR 90 TD (Gone)