No reason.
If the rings are fairly worn, you might have consumption issues.
i ll have to outline this;;when synthetics came out they had superior additives&cleaning action too,,for another thing this motor is of that time frame, what can happen is the conventional oil used in a motor leaves many more deposits around motor,,switching to a syn oil @^70k mile or so, can wash these deposits around oil passages and can easily and its not uncommon for passages to clogg, like i said this is an older motor that will be susceptible to this (not uncommon) problem. for newer motors i stand by this as a rule too, a fancy oil should wash surface(of passages&everything else), taking chances like this seem obvious to me,,a good conventional oil of diesel rated 10w-30 is my favorite, the 15w-40 is thick for my taste, and a 5w-40 must be a synthetic i do believe,,not to say ive heard the stories about such wide grades of oils,, when the 5w-30 conv & the 10w-40 conv oils came out they were heralded as the Worst thing they could do at the time,,and 5w-40 is even a wider of a gap than 5w-30, back then you stuck with 5w-20 for stability, or ran 10w-30,,
added:the base oils back then to list them any sae straight weight is ok if it works in a motor(not brand, but weight), for multi-viscosity 5w-20, 10w-30, 15w-40, 20w-50. back when synthetics first hit the main stream,, these were the weights of choice, 5w-30&10w-40 were doing terrible, too many problems with that 'gap' in the viscosity, the oils i listed(all conventional oils) were preffered and more stable than other oils(conv in this case).