Why would the Japanese not use their major battle units around Guadalcanal, instead of their oldest heavy cruisers and battlecruisers?

You guys are what make the Rock, Roll!



The Japanese Army ask the same question in the movie Isoroku https://www.imdb.com/title/tt1932695/
The ansewr was lack of fuel, but I also think the supply of ammunition would have played a role. The large 18” guns from the Yamato class could fire high explosive shells, but I guess those would be in short supply as I guess the class was primary stocked up with armour piercing shells. https://en.wikipedia.org/wiki/Yamato-class_battleship

So, for an old fashion short bombarment job the old battle waggons could do the same jobs just as effective, an to destroy an airfield You would prefer a shot gun approach with more shots of small caliber to hit the dispersed planes, as any hit of any caliber would destroy a plane or set fire to some fuel.

Funfact: Later the US would learn that a Japanese arial bomb destroyed a certain number of the metal netting when it hit the runway. Then they placed prepacked repair kits along the runway so a hit could be repaired in minuts

Furthermore the restricted waters of the Solomons is not a place you want to send the big boys. Some in the US Navy were conserned about sending USS Washington and USS South Dakota into those waters and Admiral Halsy did it only because of lack of other ships. https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/n/Naval_Battle_of_Guadalcanal.htm


This links gives a fine description of the problems with capital ships in closed waters, as it is seen from both sides.