As in the title, I have the 460 EFI in a 1990 F350 extended cab DRW. This engine has never been into in 106k miles. Truck is in beautiful shape and I plan to keep it.

1. Does this engine have flat or roller lifters?
2. If it has flat lifters should I stick with L grade oil?

I have been running Motorcraft all along and now the semi synthetic is all I can find. So now I am using the semi synthetic and change oil between three and four thousand miles, depending on how I use the truck. Truck does not get a lot of hard work. Inside the rocker cover is clean as a pin, no sign of sludge.
tia
ray