switching to synthetic

It is important to note distinctions between what are now categorized as "synthetic" lubricants:

http://www.chevron.com/products/prodserv/BaseOils/docs/ebot.pdf

I've found that the GpIII stuff made by Shell (Rotella T-Syn), is less prone to the seepage/leaking phenomenon often attributed to synthetics. As is detailed in the paper linked above, modern gpIII motor oils are now on a par with and in some areas even surpassing the performance characteristics of the original PAO-based synthetics.