Short answer - I use Amsoil
With synthetic motor lubricants and superior air and oil filters, I have options, oil change intervals 7,500 miles (12,000 kms) or 6 months whichever comes first or 25,000 miles (40,000 kms.) Save on my gas mileage and obvious superior performance and protection during extreme temperatures.
Don't assume that products that cost twice or three time more than common conventional products are too expensive. These are cost effective to the point where it saves more than it costs. In other words, it's a no brainer. Truckers can show this from their non-solicited testimonials. 

Have a look at and use - www.lubedealer.com/hiebert and find your vehicle in the Product Look-up Guide.