AstraVanMann wrote:

That's why I pay
something like £30 per 4 litres for 5W/40 fully synth for my Sprinter. And
that's got a proper high mileage engine - 206k and counting.

Same here for the Ford, the Cologne engine came with a warning that
cheap oil would carbonise and foul the oilways so it's always had 5/40
synthetic, currently stuck on 180,000 miles because I'm not using it as
much as I used to.