So I have had number of issues with my wire harness recently & found a
younger harness
that is not so brittle

so first I want to clean up the newer one change boots for the fi & there
are 3 or 4 wire that are bit
stiff so i will cut those back & re-crimp the ends etc...

But I look at my 87 bmw 325i with 300k on the clock it has none of these
wiring issues that the van has
because  it use's that split loom tubing ...
My belief is that the cheesy plastic sleeves do a poor job of protecting the
wires from the temperature
ranges in the engine compartment && the fact that the sleeve seems to always
be cut too short such that
the last 1-3" or wire are exposed rather than the enclosed in the plastic
sleeve

I think if I were to take this new to me harness strip all the low life
plastic sleeve off & replace it with
split loom tubing with thermal protection like
http://cableorganizer.com/convoshield/
& run the tube right up to each joint or connector & leave no wire ends
exposed

This issue of the wring in the engine compartment would be put to sleep for
next 5years at least

Is there any thing else I can do is there a wire dressing i can spray on
this harness to make it more flexible
Is there a better product than that convoshield/