#0 lithium is white. It's a pretty light grease. If the stuff you used is all purpose grease for ball joints, tie rod ends etc. it might be too heavy for your tiller. I don't know if will actually hurt anything, but it will probably make the engine work a little harder.

I believe my Mantis Tiller is about 30 years old.  The transmission was worn out when I got it.....as there was no grease in the gearbox.  I bought new parts and installed them.....then added grease.

Lithium is a light grease and I believe it works best as it does not get hard and move away from the gears and hide in the corners....it keeps moving around. Lithium is recommended for mower spindles and gearboxes in power tools.  Any grease is better than none.  Your tiller will probably be just fine as long as you keep some kind of grease in there and add some every now and then so that the gears stay lubricated.

Heck, man, they Gotta "spec" somethin out. Ill bet you could get by on groil. I mixed up some stuff to put back in the lawnmower rear end after it puked most of its slikkum out. I mixed grease & oil & anti-seize till I got a pretty Oooozy mix & filled it up.. been workin great for 3 years,,
You want somethin slick with enough body to not run from between gears at the first sign O pressure & thin enough to not eat horsepower,,

Yep!  Ive always been blessed with "Creative Thinking"! YOuve NO IscreaminDEA just how much trouble Ive created with that thinking,,
& No,, if you cant feel a difference in how it works or how the engine sounds, youre good,,

Lucas OIL treatment fouled up your Carb? Must be some kinda crank case vent system..

I make my own slickum for stuff like that. Some oil, some grease & some anti-sieze stirred up till I get it feeling right for the application. My lawnmower & tiller are running on my Groil concoction. Mowers been on it for about 3 or 4 years, it leaked out the factory stuff. Cant buy parts for the transaxle, its a "Not Serviceable/replace only" unit,, so, I opened it up, added my slickum, drilled a coupla holes, vented it & screwed a grease gun hose in it. Now I can add stuff with a grese gun, but since I vented it, it doesnt pressure up & spit goo when the temp goes from 40 degrees to 95.. so, Im not having to add very often,

You can buy a squeeze tube of white lithium grease. I got one at a heavy equipment dealer. Cost 4 to 6 bux,, I also keep a spray lithium handy. Thats what goes in door hinges on cars. Dont spray it on pressure contact points & make things slide instead of roll, just on axles that have wheels or stars that turn & hinge pins.