Do it. Mobil 1 High Mileage
Oil might be the right choice. I have done the same thing many times & subsequently put tens of thousands on the engines without issues. As noted above, an
oil and filter change after 3,000 miles would be a reasonable precaution against newly dissolved sludge.
However it is likely that a quality conventional
oil (with detergents) will have prevented any sludge built up.
Z.