Hello Karl

Oil change: select just one drain plug to drain & one filler to fill smile
The oil Kirby recommended was a straight SAE30. Some members use multigrade.

Service Guides:
Also note service guides No. 57 & 58 supplied by bestseller:-
Guide 58 is on the carby.
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=58949

Hope this helps.
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Jack