If you have jeep 2002 grand Cherokee elimited 3.1 diesel there is oil goin in too coolant degasser bottle?

If you're seeing oil in the coolant degasser bottle (overflow reservoir) of your 2002 Jeep Grand Cherokee 3.1L diesel, it's a serious problem indicating a head gasket failure or a cracked cylinder head. Oil and coolant shouldn't mix. Their presence together signifies a breach in the barrier separating the engine's lubrication system from its cooling system.

Do not drive the vehicle. Continuing to drive will cause significant engine damage and potentially catastrophic failure.

Here's what you should do:

* Stop driving immediately: Further operation risks severe engine damage.

* Have it towed to a qualified mechanic: This isn't a DIY repair; a professional needs to diagnose the precise cause and perform the necessary repairs, which will likely be extensive and costly. The repair could involve replacing the head gasket, the cylinder head itself, or possibly other related components.

* Document the issue: Take photos or videos of the oil in the coolant reservoir as evidence.

While other less likely possibilities exist (a cracked engine block is extremely rare but possible), a head gasket failure or a cracked cylinder head is the most probable explanation given your description. Get professional help right away to prevent further damage.