Hi everyone!
Just did a long journey in my 95 discovery 300tdi.
800 miles from Folkestone to Cambourne in cornwall and back in one hit. All this with a horse trailer!
Did great but on the way back the oil light came on. Now I topped it up before I left and thought it must have burnt the oil cause of the heavy load. So I topped it up (half to a whole litre) with what I had assuming it would be below the min mark.
Did another stint and at some lights it did it again. So I stopped and bought a litre at great expense(£15)
But it all in.
When I got home I checked the oil properly and it was now above the max!!.
Looks like I Hardly used any oil but why would the oil light come on at idle. Heavy load? Rings? Pressure switch?
Now there is no load it seems fine again???

Could be your oil not been changed & gone thin with heat from the journey.

If well maintained change the pressure switch as cheapest

Hicap phill said:

Could be your oil not been changed & gone thin with heat from the journey.

If well maintained change the pressure switch as cheapest

Click to expand...

I service it every August with new 10/40 oil. Due a service very shortly so it will be treated to new oil very soon.
Won't hurt to change the switch though.
Annoying though as I had it out nine months ago to do the o ring as it was leaking!.... Lol

I have the same problem, and my engine was rebuilt fully less than 2k miles ago. Only happens when i rag it so I assume its the oil getting really hot. Still, it shouldn't happen.

IME, the oil pressure switches are a weakness on D1's - When SWMBO's oil light came on - I checked the pressure with a gauge - was 60 PSI - so clearly not low pressure - New switch ordered ..... before this turned up, she went to work ( I mean, how rude, having to go to work ) - and the blo@dy switch burst - what a friggin mess .........

As above - first port of call is new switch - but I'd also check the pressure with a gauge to be sure

I did consider a warranty claim on the switch - it had only done 100K miles and 22 years - so quite poor really