Could not agree more.

Diesel at £1.40 a litre costs me £50 for 2 weeks.

Oil to manufacturers specification and filter costs me approx £30.

Thus over a year the oil and filter change costs me less than 2.5% of my fuel costs.

On my "classic" I change the oil every year even though it ony does about 2000 miles. The cost of an oil and fiter change is a fraction of the cost of an engine rebuild.

But there are a lot of very strange people out there who insist on doing the daftest things to save a few pence.