However, here are some potential causes and what a mechanic might check:
Possible Causes and Diagnoses:
* Worn Valve Stem Seals: These seals prevent oil from leaking into the combustion chamber. Worn seals are a common cause of oil burning, often resulting in blue smoke from the exhaust, especially on startup or acceleration. Repair involves removing the valve covers and replacing the seals.
* Worn Piston Rings: These rings seal the gap between the piston and cylinder wall. If worn, oil can seep past and burn in the combustion chamber. This usually results in blue smoke, often consistently. Repair requires removing the engine head and potentially the engine block, a significant undertaking.
* Leaking Valve Guides: Similar to valve stem seals, worn valve guides can allow oil to leak past. This also often manifests as blue smoke from the exhaust. Repair involves replacing the guides.
* Breather Hose Issues: The positive crankcase ventilation (PCV) system vents crankcase gases. A clogged or damaged breather hose can cause excessive pressure in the crankcase, forcing oil past seals. A relatively easy fix, but often overlooked.
* Damaged or Worn Cylinder Walls: Significant wear on the cylinder walls can allow oil to leak past the piston rings. This is a serious issue often requiring a rebuild or engine replacement.
* Improper Oil Level: While seemingly obvious, consistently overfilling the oil can cause it to be burned. Conversely, *too little* oil can cause engine damage leading to increased oil consumption. Always check your oil level regularly and use the correct type and amount of oil.
Troubleshooting Steps (For a Mechanic, or a Very Experienced DIYer):
1. Check the Oil Level: Make sure the oil level is correct. Consistent overfilling should be addressed first.
2. Inspect for Leaks: Check for external oil leaks around the engine, transmission, and other components. A leak might be mistaken for burning oil.
3. Check the Exhaust Smoke: The color of the smoke can provide clues. Blue smoke usually indicates burning oil. White smoke usually indicates coolant leaks. Black smoke usually indicates a rich fuel mixture.
4. Compression Test: A compression test can help determine the condition of the piston rings and cylinder walls. Low compression in one or more cylinders suggests a problem with those specific cylinders.
5. Leak-down Test: This test helps pinpoint the source of compression loss, further identifying worn rings, valves, or head gasket issues.
6. Visual Inspection (With the Engine Apart): A mechanic will visually inspect the critical components once the engine is partially or fully disassembled to determine the precise cause.
In short: Don't try to fix this yourself unless you have extensive experience rebuilding engines. Take your Windstar to a qualified mechanic for proper diagnosis and repair. Ignoring the problem will likely lead to more significant and expensive damage to your engine.
