[chrisseaton]

A counterpoint to this is that my car is manufactured in a single plant in Europe. It ships with engine oil in it (because it's driven on and off the transport ship). So I presume one sold in the UK and the US have the same oil in, yet Land Rover will tell you to change that exact same oil in the exact same engine after 20k miles in the UK and 5k miles in the US.

[Spooky23]

There’s a weird subset of Americans who are very “passionate” about motor oil. They argue about oil filters and formulations… almost audiophile like.

My guess is the guidance is to avoid some PR nightmare.

[aronpye]

Fuel and oil quality is a lot more variable in the US, so are the environmental conditions, so you have to set the guidelines according to the minimum likely to be encountered.