So, we've got a 1995 Pathfinder XE V6 with 180,000km on it, and it burns oil like crazy (approx 1 litre per 500 km!). The trick is, that it only seems to burn oil on the highway, when the engine is good and warm. There's no blowby, the PCV valve and intake are clean as a whistle. I can do the trick where you step on the gas, and then back off, expecting to see blue smoke that's come by the valve seals...nothing. In fact, there's no evidence of blue smoke in any sort of normal city driving.
So, I'm wondering if perhaps the catalytic converter is plugged, and it's causing the engine to overheat, causing the oil to burn off. When I checked the oil on a recent long trip, it always seemed to be quite dark when I topped it up, even when I had only changed it with fresh
5-600km ago. The coolant temperature seems good most of the time (approx. 1/3 of full scale, occasionally higher) Does my assumption of the catalytic seem like a reasonable one? Any other thoughts which may help me track this down? I understand that it isn't a particularly easy thing to check, but may be worth a try, considering the truck is almost 10 years old?Any help is greatly appreciated. Thanks, Stephen