I also bought my '89 B-2200 in September, but it was in '92. =)
Re: oil leaks - the one nagging problem I've had with my truck ever since I've had it is that the front camshaft bearing is exposed (not covered by the valve cover).
It is where the distributor attaches to the engine.
That sucker has leaked oil ever since I've owned the truck.
While I'm still quite pleased with the overall performance of my truck, this is one problem I wish I didn't have to deal with.
According to the factory shop manual, one can apply Permatex to the mating surface of the bearing cap and/or the head, to step the leak.
I did this when I rebuilt my engine in '95. I made it maybe 50 miles when I heard a very quiet "pop". It was oil pressure breaking the seal created by the Permatex (engine had a new pump, too).
At that point, I conceded to simply keep an eye on the oil consumption and refill as needed.
I generally do O&F services at either 2000 miles (stock Napa 1357 filter) or 4000 miles (Napa 1347 filter for older 2L engine, which works fine on this one, offers twice the amount of filter medium and makes accessing the filter a whole lot easier).
I have noticed that right around the 4000 mile mark, the engine does tend to use some oil, but typically, I only need to add about one quart between services.
One thing that helped slow the leak (and quieted a lifter tick I was dealing with at the time) was to switch from 10W-40 to 15W-40 Delo 400 (Rotella will work, too).
In the early 90's when I made that change, the only way to find that weight of oil was in the "big truck" brands, such as those I listed.
They also had a high Zinc content and this is what quieted the lifter tick (commonly listed as "special upper engine/cylinder head lubricant").
Unfortunately, the EPA has reared its ugly head again and they mandated that those brands lower their Zinc content (look on a bottle some time, you'll see a "Low Zinc" badge now adorns the label), and thus, the lifter tick is back.
Once my engine hit the 100,000 mile range (that's 100K on the rebuild), the oil usage started to increase.
I circumvented this, somewhat, by moving to 20W-50 (switching back to 10W-40 in the winter).
It works to some degree, but I feel that another rebuild is in the offing, soon.
Check around that front cam bearing cap, with the engine warm and idling, and see if you don't see a little oil pumping out from there.
Could very well be where your leak is.
It's probably the o-rings need to be replaced. If it blows a little smoke, that's your problem. I have the same truck and the same problem. Although it's been a VERY reliable vehicle thus far!
That's very good. I also had it good (239k miles) until recently I changed the distributor. It starts and I rev it up for around 5 minutes, then it just dies like it ran out of gas. I try to restart, but no go. The next day I can do the same thing. Does anyone out there ever experience the same thing?? Anyone out there have any suggestions???