[M.D. Holloway]

Milt,
The first number is what it is winterized to, the second number is far more important. The older 2.7 needed a SAE 50 at operating temps (above 100C) - the fact that it was a 20W50 is because years ago they just didn't have pour point depressant technology to bring down the low temp viscosity. That is not the case. You can find 0W40 on the market but really if you don't live up in the Northwest territories you don't need it.

In fact, if your car never sees temps lower than 60F, there really is no need to use a winterized oil - you can stick to a SAE 50. I have known many folks to drop a viscosity grade without incident and actually save a little of gas costs.

So - you can actually use a SAE 15W40 if you drive in the winter (sub 40F) or a SAE 40 if you live in Hawaii.