NEW JEEP - BREAK-IN / OIL CHANGES

[TheTanSedan]

My wife has an '01 Cherokee with the 242 straight six. Changed to Mobil 1 10w30 at 3000, then to Mobil 1 0W-40 after a 1k treatment with Auto-Rx at 36k.

Changes are at about 6k, with Mobil 1-301 filter. Vehicle sees an average 500 miles/week in business driving (mostly freeway), consumption is zero. Never any piston slap (wasn't even aware it was an issue with these motors until reading on another board).

Auto-Rx removed an incipient varnishing/glaze as observed in oil cap; used mainly for peace of mind. All other service is well-ahead of schedule.

This vehicle is driven conservatively (looks like OEM brakes and tires will both exceed 75k before replacement mandatory), but also runs in extremely hot Dallas weather.

Mobil 1 0W-40 was chosen for any slight advantage it would have in hot running conditions.

 

[JonC]

TanSedan,
Did you notice any difference in running the 0W40 vs the 10W30? Have you done any UOA? I've been running Mobil 1 10W30 for 70K in my '99 4.0L engine, but have recently entertained the idea of trying out the 0W40.

Jon

 

[TheTanSedan]

No UOA yet, am waiting to change to a second fill of Mobil 1 0w-40 before a 2100-mile roundtrip in early May, and expect the next change in mid-late July. That will be a period consistent with the hardest running for the car as daytime temps will be exceeding 100F, nights at or near 90F, and constant A/C use during operation in a period of summer with the highest ambient humidity. This vehicle has such poor underhood airflow management that it takes -- literally -- a pair of leather gloves to open the hood.

That is the point a sample will be drawn and the Blackstone/Dyson analysis done.

0W-40 will have its mettle tested for this vehicle during this period.

This is also why I have -- on the OIL FILTERS forum -- posted questions in regards BALDWIN and DONALDSON filters for this car to try (as Terry Dyson has indicated a preference for) an easy flowing fiberglass media filter.