I own a Jag XJ N reg and last year when I collected it from the garage after its service and MOT the garage informed me that they had crossed threaded the engine oil outlet nut.

They ‘reassured’ me that ‘as you don’t do many miles it wouldn’t matter too much!’

Well, it’s now been a year since my oil has been changed and although I’m 86 I would like to think I can enjoy a few more miles in this wonderful car. My friend, who has always serviced my Jag in the past (but has since retired) and is 86 too, has informed me that once he got around this problem by finding a larger nut and rethreaded the female on the sump to suit this nut.

Unfortunately, in this case, there is not enough metal around the plug to thread a new one and it seems the only resolution to this problem would be to remove the engine and replace the sump.

Your correspondence a couple of weeks ago referred to pumping the oil out via the dipstick channel but you were against this idea as the sludge would remain in the sump.

However, would the filter prevent this sludge build up in the first place? I assume he had the same problem as me and if you are a limited mileage motorist surely this is the only sensible solution to this problem?