my 2005 truck - Walmart Synthetic (likely Group 3)- change every 5000 km (about twice yearly)
1976 motor home - conventional oil, change every year or two (use about 500 km yearly)
13 year old lawn mover - top up with the cheapest oil I can find, never change oil, hoping this is the year that it stops running like a top so that I can buy a new shiny lawn mower at Walmart for $150
I am not recommending these OCIs, just reporting what I do
*how often should you change oil in a seldom used vehicle?
p.s. - we Canadians do not dump oil in our rivers and over 50% of us don't live in igloos anymore