Fortunately, most name brand oils meet API SJ at the current time since API SM is the latest spec.

There is no specific single grade recommendation in the owners manual for oil. Rather, it is a chart based on ambient temperature range.

The "5W-30" comes from the single one-liner "for maximum fuel economy". Note that it says nothing about "maximum longevity".

The trend in recent years to ever lower weight factory fills comes from the requirements to meet fuel efficiency targets like CAFE. The latest European ILAC rating system does the same thing. The use of these light oils can make a 0.x mpg difference in testing.

Any particular owner might decide that engine longevity is more important than 0.x mpg, and that CAFE is irrelevant after purchase.

++

 

Hi plumsauce ,

my supplier had a wide range of 5W30 oil types on the shelf , even different ones from one brand .

He explaned me that it is important to use the right one with typical additives added.

Kroonoil has a nice recommendation sheet and not all oil specs suit the XJ , so "grabbing a bottle" is not wise imo .

Catalogue - Kroon-Oil

 

The oil spec in JTIS for a 1999 XJ :

 

Who said anything whatsoever about "grabbing a bottle"?

Researching specifications properly is much better for real decision making than listening to some random parts counter guy. For all you know, he was selling shoes the week before.

 

And it says API-SJ. Exactly what was said. What's your point?

 

I was not trying to be a smart *** here ;-)


My point is that not all (for example) 5W30 oils are compatible with our cars , that's all.