Did it pass last year?
The carb is VERY important.
Is it Mitsu?
Does it look like the engine top in the Vac Hoses pages on my web-site (link in my name below).
The Weber usually will not pass smog test according to the USA members who have switched to them.

If it's just the oil, what's in there right now?
If it's cheap no-name thin stuff, try new filter and the Castrol Deisel 10W40, take it for a good 200km highway run, and then try passing smog test immediately after while the engine's hot. Pick a time in the day when there's no line-up, the idling will hurt you.


I might still have 2 spare Mitsu carbs in a box somewhere here. But you still need the hoses in there, and the controlers. I think I still have a spare rad here somewhere too. And an alternator. Etc.