It won't hurt the engine. Unless you are in an extreme climate (very hot or
very cold), you plan on working the engine very hard (heavily loaded truck
or towing a large trailer), or you plan to go to extended oil change
intervals (>5000 miles), there is not much advantage to synthetic oil. As
long as you stick with the same viscosity it won't give you a measurable
increase in fuel economy (compared to the correct same grade "energy
conserving" conventional oil). And if you are using a quality API certified
conventional oil of the correct grade and changing it at the Ford
recommended interval, it is not going to increase the life of your engine
significantly. Don't get me wrong, I do believe good quality synthetic oils
are "better" than conventional oils. I just don't think the better qualities
are needed for most vehicle owners. There are plenty of cases where it is an
advantage, but you need to evaluate your personal needs and decide if it is
right for you. Many synthetic oil users develop a religious fever for the
stuff. They have justified the high cost of the synthetic oil in their minds
and become evangelists and try to convert everyone to their belief..
However, there is almost no real data that supports the notion that
synthetic oil is the rational economic choice for most vehicle owners. I
have (and still do) use synthetic oil in some of my vehicles. If nothing
else I like using the "best" stuff even if I know it is not really
necessary.

Regards,

Ed White

Regards,

Ed White