Good point, George. I did wonder if this is an unanswerable question.

RE: Mobil 1 viscosity, I had been using 15W-50 but switched over the the 0W-40. Maybe time to go back to the other weight.

Here's a new question for you: my local independent thinks that using the 15W-50 makes it more likely for the oil tube caps to come off (since oil pressure runs a bit higher with the higher viscosity oil). He just checked 'em and they're still on, so I figure if they've stayed on for 150 k miles they will probably stay on. Any concerns about the 15W-50 being too high a viscosity?

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Steve
'93 400E