Smoky exhaust, only in Canada

[TJ D]

Hi,

I've been scratching my head on this one, maybe somebody knows the answer to this.

We were cruising in the Canadian Maritimes this summer, and when I got into some fuel we'd taken in Halifax, then again with some from St. Johns, NL (diesel 2 in both cases, I checked), We started to see quite a bit of exhaust smoke, grey/black in color. Once we got back into fuel purchased in the USA, poof! It was no longer smoking. I found this to be quite curious, as many of you might imagine. I mean, we see what I consider to be a normal wisp of smoke at higher revs now as we always have, but there was substantially more when burning the Canadian fuel.

Here are some particulars on the engine.

2500 hours, naturally aspirated 70hp
Injectors replaced at 2200 hours.
Good filtration.
Air filter clean and unobstructed.
Smoke was worse at higher loads.
No coolant loss.
No oil loss.

So, does anybody know if Canada uses a different formulation that might cause this? Less/more sulfur? I was really scratching my head on this one with the new injectors and all, so it was a relief to see it straighten out, but it's something I'd like to figure out.

Any fuel gurus out there?

Thanks, TJ