about oil change

Your mileage indicates you drive less than 6,000 miles a year. There are lots of opinions about engine oil, change intervals and type of oil to use. Short trips suggest you should change your oil more frequently. I think you are fine changing your oil every 3,000 miles/ every six months and stay with conventional oil. Does your engine burn oil to the point where you have to add a quart or more of oil between oil changes (assuming you have no oil leaks).? If you have to add oil move up on viscosity level of oil instead of say 5/20 W use 10/30 W. No Smoke is an engine oil viscosity increaser. My thought is if you have to increase the viscosity of engine oil between oil changes by using an additive why not start with an oil that has slightly higher viscosity to begin with.

I can't speak to the smoking issue. Hopefully someone else can. You can go longer than 3 months for oil changes, from what I've heard. You could go as long as 6 months, if the miles are low--this is what I do, and my technician says that's not a problem. If you have been using regular oil, I don't recommend changing to synthetic, as the additional detergents in synthetic oil could cause problems in an engine that's used to running on regular oil.