Synthetic oil. Can it Really Go 10,000 miles?

[SirDigby]

another thing to think about with going so long on oil changes is contamination of oil. every time it warms up/cools down it collects condensation. blow-by at the pistons adds fuel to oil. this is what the filter is for, but it contributes greatly to oil break-down. it's not always a good idea to go as long as possible on oil changes. time is a factor. if you drive non-stop for 5000 miles, the oil will be in almost new condition, where as if you drive 5000 miles a year, the oil will be in much more poor condition...