Ron,
Unfortunately in your case, the smoke is most likely due to sticking
rings... a problem with those loveable ole D24 engines. Heavier weight oil
will help I believe, and maybe even some Lucas Motor Oil Stabilizer (Motor
Honey), but your best current bet is going to be a product called AutoRX
which will help un-stick those rings:
http://www.auto-rx.com/
The best stuff was Lubro-Moly OL Shalaam Spulung, but since it was imported
to the USA/Canada as "Engine Flush", the contents have changed significantly
and it's not very effective anymore.
If you really want to cure the problem for good, a rebuild is in order.
Replace those rings and change your oil ever 3000 miles after your rebuild
with quality stuff (or 7500+ with quality synthetics) and you'll be good for
several hundred thousand more miles without problem, and much more
power/less smoke. Volvo's worst call ever was putting 7000 mile reccomended
oil-change intervals in their 1980's volvo diesel owners manuals... it sent
most of em to the junkyard at right around 160,000 miles. Anything to make
a diesel sale in the 80's, eh?
By the way, a few of us diesel-brickers have a Yahoo! group just for us...
come on over and join up!
http://autos.groups.yahoo.com/group/volvo_diesels/
If you're an '86, you must have the last year of the 740 Turbodiesel...
invest some time and a few dollars on that rebuild, and you can push 270hp
out of that little straight-6 while getting 46mpg on the freeway at 75mph -
It's been done! There's a lot of potential in that engine...
-Mike
82 Volvo 245GL Diesel