Stan;
Maybe it would help if you tell a bit more on the circumstances of this "old" wood!
In general, un-treated wood seems to get gray and often do a lot of splitting and the surface seems to get rougher and rattier-looking over time. I'm thinking here of your typical old boards, wood window-frames and house trim, and the like.
Much the same graying-out happens to peeled logs, as in log-houses which are not stained, sealed, or re-painted.
So, in general, old wood is gray wood - sometimes with stains and the like.
IMHO, the BEST way to create the old wood effect is to use some real wood and roughen it up some, work in some splits and maybe some peeling-off bits, and paint it up with gray washes. Again, this would work best on boards and logs and such that can be easily made from real wood. Old shovel handles are not much different, save that they may have started out sealed or varnished, and so maybe having some darker "sealed wood" patches painted in wood browns and tans (take you pick!) interspersed with grayer rougher areas could work.
Hope this helps!
Bob