Why oil firing was not ready for HMS Dreadnought

Could HMS Dreadnought have been built with oil-fired boilers?

The technology existed in experimental form, but navies had not yet built enough confidence to use it in a capital ship of Dreadnought's importance.

Oil-fired propulsion was already being explored, so the technology was available in an early form. It was still insufficiently mature or trusted for a capital ship when Dreadnought was designed. Navies commonly tested new machinery in cruisers because those ships were large enough to provide useful evidence but less costly to discard if the experiment failed. An oil-fired Dreadnought was therefore technically imaginable but premature as a fleet standard.