I have 1998range rover what oil grade i need over 140k mile

You have frayed wires to the light, or light switch.

depends on your mileage since its an older vehicle i would would 20/50 synthetic esp if you in the warmer areas

could be low level/oil/pressure so not getting around the rockers quickly enough . i'd advice a oil and filter change , use the best grade oil recommended for your vehicle

Many engines begin to drink oil at or around 100K miles. I found that Castrol GTX High Mileage oil will get me to the next oil change (at 5K miles) without having to add a drop, where as before I made the switch I was having to add two quarts just to get there with the generic stuff.

I found 2 listings for the 2.0L engine, A and B. The 'A' had no info on oil type, the 'B' stated all temperature ranges require type 'SJ' and 5/30 or 5/40 weight. Because the mileage is 140k, I am wondering how often you must add oil between changes. If you add none, or under a quart, 5/30 is ok, if you must add oil more often, use the heavier weight, 5/40.

15w40 is reccomended

The maintenance schedule is an outline and should be followed if you want to keep your vehicle in good condition. the maintenance items listed in the schedule are performed at their set intervals for a reason. Manufacturers have found the wear limits on certain parts and those parts may need to be serviced or replaced at those intervals or catastrophic failures may result.

Hi if you park your car on a level surface do you have any patches on the floor?
If you do then it would point to Front or rear main seal. However it is a very common fault on 4.0l and especialy 4.6l to crack piston rings. The sumptoms are high oil useage and mostly no trace of oil leak and normaly no signs of smoking either.
Thanks Rob.

Use 5w30 oil in this car, preferably a synthetic. The manufacturer recommends this grade of oil and it needs to be changed every 3000 miles.