I drive my pickup about 1000 to maybe 1500 miles a year. It used to be change oil every 3 months. I would think that would be ludicrous. I believe I should change it every year, but can I go longer?
Also I only drive my car 6000 miles a year. With synthetic oil can I change it every year?
depends on the weather mostly. If you have subzero winters, or over 120 summers, as in some parts of the country, you need to change it seasonally. Use a good multivis, or a synthetic, and change it every 6000 if you live in say so. cal. Some guys would go 10k and some are religious at 3k. It is personal, unless you are under warranty.
If either is still in warranty for the powertrain, follow the manual. If out of warranty, follow the manual. You might convince me to to to once/year (max) if the miles you drive are accumulated 20-30 at a time (say, once a week) and the vehicle gets thoroughly warmed up most every time it’s driven.
I would keep changing the truck’s oil once a year but change the car’s oil twice a year, regardless of what kind of oil you use. It’s the additive depletion that makes you need to change oil. If your car has a turbocharger or the manufacturer calls for synthetic, use it; otherwise you are wasting money. Changing oil every 3000 miles with normal mineral oil is much better and cheaper than changing oil every 6000 with synthetic.
If all your car driving was cross country, 6000 miles itervals would be OK.
But it looks like you do the worst kind of short trip driving with your car and even synthetic would need to be changed spring and fall.
Thanks for the answers so far.
Clarification, yes we do get 20 - 40 below, but rarely above 90 here.
But usually don’t drive either more than once or twice a week – have an office at home 
And town is 20 minutes/ 10 miles away. And about once a month maybe drive a trip to the big city.
I was sold on synthetic when I drove more, but it does seem like a waste with our driving habits.
What does your manual say? Why don’t you want to follow what it says? Is the car still under warranty?
If you use 0W30 synthetic in the winter and a 5W30 non-synthetic in the summer in your car, that would be the best for long engine life. Better yet, install a block heater to turn on 1 1/2 hours before you leave the house.
As far as the truck is concerned, one oil change a year is best with 5W30 synthetic if you use the truck in the winter. If you use it mainly in the summer, use a 5W30 mineral oil and change once a year.
[b] Read the owner’s manual. It will say XXXX miles or XXXX months which ever comes FIRST
I guess I should have stated what to me was obvious. The reason to change seasonally is you need different weight oil in subz than in over 90 temperatures. Oil lubricates, but it also carries heat, to cool in summer and distribute in winter. A heavyer oil will run thinner in hot conditions, a lighter oil will run thicker in colder times. The manual will tell you which and when as long as your vehicle is in warranty, but aging vehicles have more wear already, and you want good clean oil, or if it is a beater that you are driving into the ground anyway, maybe you just want to add when it is low. I maintain it is a personal choice, but I am not the guy who is going to have to fix your engine when it throws a rod either.