Hi.10w30 was fairly common in the UK until ACEA oils came onto the scene.
any a3 oil will be more than enough
I looked on the site of one of the big lubricant suppliers here in the UK. Out of the hundreds of engine oils, they offer just the one 10w/30. Very odd.
The Jeep belongs to an acquaintance of mine. I will advise a good quality 10w/40 semi synthetic. If he really wants to use fully synthetic then a 5w/30 or 5w/40.
If the Jeep has been run on semi synthetic, will a change to fully synthetic cause leaks? Is this an urban myth?