I'd run through a cheap 10w-30 oil with Rislone additive for 1500 miles to clean it really well, then run through a part synthetic with Marvel Mystery Oil for 3000 to get everything running smooth and lubricated.
/ 2002 WJ 4.7 H.O. / Flowmaster 50 SUV / Magnaflow Cats / Rocking that 2WD! /
Just about any name brand full synthetic in 5w30 should clean up any residue and treat your engine well in the process. If you're not a synthetic guy, I'd suggest conventional Pennzoil 5w30 in the yellow bottle, it is higher in detergents than just about any other name brand oil so also a good choice if you're not sure how clean it is. Valvoline Maxlife is also very high in detergents and would be a very good choice as well as it also has seal conditioners which can't hurt for our aging WJ's.
But be careful with Pennzoil, it starts turning colors at about 1500 miles and you need to change it around 2000.
That's because it's cleaning, but that has nothing to do with how well it's lubricating Like I said it is higher in detergent than any other conventional, but oil can both clean and retain it's lubricating properties all at the same time.
You don't need to change it any sooner than anything else.
Some of you must have some real clean engines! When I ran petrol (gas) engines I always run an engine oil flush through to get rid of as much dirt as possible before I change the oil andthe new oil is ALWAYS dark within a 1000 miles or so.... short of taking your engine apart and cleaning every part thats how it will be and is perfectly normal.
I run a diesel now....and its it new oil is black almost instantly...because diesel engines stay dirty no matter how you flush them. Does not stop the oil staying in for the full 12000 miles (that is the correct interval for a CRD before all you 3000 mile change gas engine owners have a heart attack!)
If you can't fix it with a hammer, you've got yourself an electrical problem!