Is the sierra gimbal bearing still the preferred bearing over the mercruiser bearing due to not being greaseable.
The part number for the sierra bravo bearing is 18-21005 which is greasable.
The mercruiser permalube bearing part number is 30-879194A01 is not greaseable.

Non Greaseable and Sierra makes them as well. Just the same as non greasable U joints. Have no idea were people get the notion that the greaseable ones last longer. These Non greaseable ones have been in service now for 11 years and have yet to see one fail from being greased starved. Not one. Actually the sealed ones holds more grease internally especially during rotation were the greaseable ones seep out grease as they become warmer.

I have all and any version of Gimbel Bearings in stock if needed. The most important thing is to use the correct version of Gimbel Bearing per your serial numbers. I have explained all of this in full details up here a lot.

Water and sitting idle for either bearing is its worst problems.

The manual says to grease once per year. HOw often is too often?

one is you do not want grease laying in the U joint bellows so over greasing does nothing but runs out all into that area - both are petroleum products from the very start, but way different chemistry so with that said what happens is the grease attacks the rubber composition of the bellows and degrades it over time. It actually over periods of time turns the bellows very soft and very weak from the inside out. The best way is pull the outdrive - inspect all including GB, bellows and U joints, alignment and so on - grease GB turn one 1 /4 turn grease and continue that all the way around. Wipe off all excess and anything laying the bellows.

Repeat - the real way to grease the GB is by rotating it and greasing. Also some greases are not compatible with each other. Use the proper grease and stick with it thru out its course

I have no problems with the sealed Gimbal bearings period. I prefer them over the greaseable ones. My experience is not with one boat related but in the thousands of apps with both non geaseable and greaseable GB's. Volvo Penta started using the NON greaseable GB one year before Mercruiser did. Believe it or not Volvo does spend a lot of time with R&D and testing their systems. This is one area they spent some time with as well.

Thanks for the info. Rather than pulling the drive to grease the serviceable bearing; how about a squirt each time after taking the boat out? Surely the bearing will be in a different position each time.

slowly grease the outside GB zerk while the engine is running at its lowest idle speed but be careful of CO and prop related mishaps with yourself..