They definitely needed regular servicing including flushing out the radiator if not every year, certainly every second year.
Many ran up huge mileages reliably but were defeated by structural rust.
Now, here is an understatement........
Camshafts used to seize in the head (with catastrophic results) because of oil starvation when the oil feed became closed.sorbs wrote: I think there were issues with oil supply to the camshaft too.
I have heard this being blamed on a lack of servicing but don't know how correct that is.
My late father considered buying an SD1 2600 but didn't like the low seating or the exterior colour. That particular car had a brand new engine despite a total mileage of less than 20,000

