[brucepick]

OK, it's off topic, but what the heck - - -

I was losing oil at a pretty good rate. Between 2-4 oz per hundred miles, which is between just under a half-quart to a quart + 8 oz per thousand miles. Thicker 15W-40 oil was the only way to keep the losses down in that range!

I finally figured out the cam shaft o-ring seal at the distributor was the culprit. Replaced it and now I dare run thinner oil.

Yes I do want to try 5W-30 after I've had some experience on the 10W-30. But the engine has 250k miles on it, likely the rear main seal is not too good, either, and the rings might not be sealing that well either. The rear main is a much bigger job to change than that little o-ring I replaced. I had the head rebuilt in Feb-March of 2011 so I trust the valve seals + guides are OK.

The oil's 5W- or 10W- rating is the cold viscosity. With a 1 hour commute, the engine is cold for a small percentage of its running time. So I wouldn't feel bad about the 10W- rating if I use that through the winter. Mostly the oil will be running in the -30 range anyway, just as if I would be using 5W-30.