A similar question to my previous question! LR manual say to use oil meeting: API SM and also ILSAC GF4 specs. I'm having trouble finding an oil that meets the second qualification. I do find Castrol meeting GF6 specs. Is this OK or do I need to search further for something specifically meeting GF4 specs? Of course I can order the LR oil . . . but big $$.

 

I use Castrol GTX 5w30 (plus Wix filter) every 5k miles, and am almost at 190,000.

 

You shouldn’t be able to buy ILSAC GL-1..4 anymore. It’s fine to buy GL-5, it is backwards compatible.

ILSAC GF-6A is backwards compatible with the older specs while GF-6B is NOT.

In practice you can either hunt for an oil matching STJLR.03.5003 or one of the Ford ones WSS-M2C913-D (or -C or -B). -D is backwards compatible with the previous ones (C, B, A), C is backwards compatible with (B, A), etc.