I've been looking through Catagolue to see if it has any syntheses for oscillators in my collection that are >= 1 glider/bit. It has removed most of the P4s from my list (except for the few I haven't had time to examine yet). I did notice that it's using a sub-optimal mold converter; the one below is cheaper.

`x = 76, y = 21, rule = B3/S23`

boo28boo18boo18boo$obbo8bo17bobbo16bobbo16bobbo$obo8boo17bobobo15bobob

obb3o10bobobbo$bo9bobo17bobo17bobo3bo13bo$5b3o24bo19bo5bo13boobo$7bo

48bo17bo$6bo44boo3boo$50bobobbobo$7boo43bo$7bobo$7bo8$20bo$19boo$19bob

o!

One 21-bit cuphook had a 77-glider synthesis, but Catagolue doesn't list it. Fortunately, it has a soup that reduces this to 11. It might be possible to reduce this by one or two by using a 3-glider pond+bit spark above, and/or a less obtrusive 3-glider wing to allow a 2-glider bit-spark on the left.

`x = 88, y = 33, rule = B3/S23`

59bo$58bo$58b3o4$33bo$34bo$32b3o4bobo$40boo$40bo3$22boo28boo$bobo17bo

bbo26bobbo12bobo14bo$bboo17bobbo26bobbo8bo3boo14bobo$bbo19boo28boo8boo

4bo14bobbo$62bobo15boobo3bo$boo77bobbobobo$obo80boboo$bbo80bo$35b3o43b

obo$37bo43boo$36bo$49bo4boo$49boo3bobo$48bobo3bo4$56b3o$56bo$57bo!

EDIT: Another reduced from 36 to 17:

`x = 198, y = 83, rule = B3/S23`

121bo$120bo$120b3o31$28bo49bo$o26bobo47bobo$boo24bobo47bobo$oobbo23bo

49bo$4bobo87bo$4boo86boo$33boo48boo8boo$32bobbo39bo6bobbo$33boo41boo5b

oo$75boo3$67bo$68boo$67boo112bo$179bobo$180boo$$39b3o47b3o57bo29bo$62b

obo83bobo27bobo$63boo83bobo27bobo$6bo56bo69boo14bo13boo14bo13boo$6boo

63boo61bo29bo29bo$5bobo57boo5boo11b3o46boboo26boboo26boboo$10boo54boo

3bo13bo45boobobo24boobobo24boobobo$9boo54bo20bo44bobbobo8bo15bobbobo8b

o15bobbobo$11bo63bo58boboo6bobo17boboo6bobo17boboo$75boo57bo8bobbo17bo

8bobbo17bo$74bobo55bobo9boo16bobo9boo16bobo$132boo28boo28boo$83b3o$83b

o$79boo3bo$78bobo$80bo13$44b3o$46bo$45bo!