Stretching Generator Oil Change Interval

Where are these globe impellers sold?
The mains as well as the Gen?

My pumps are a royal PITA to get to so anything that pushes that out is a bonus

I look up the engine or match the size. With that part number I shop the web.
https://www.globemarinedirect.com/Find-Impeller-s/180.htm

They do not make any for my mains,, yet..

You could look into bypass oil filter system, such as Amsoil(no affiliation) to extend oil change interval.

I tried them back in 2008 in the early days when they came out on a set of 12v71's, pulled out into Ny harbor and port main engine was overheating and not pumping water. They had a tendency to bend too much back then, switched back to traditional impellers and never looked back. Things might be different now, but I tend to stick to OEM unless given a really good reason not to.

Yep, back then the veins flew and could not pump much/any water on small to 250HP engines. I have been avoiding them since.
UNTIL another try in the last couple of years on NL gen-sets. We were going thru rubber impellers just to fast and had to experiment. Seems to be our fix.
I don't know they offered big HP impellers, they don't now. I do look forward to more small impellers to experiment with.

Good thing I haven't been onboard. That comment would be bass ackwards.

I had that happen years ago with a 20 kw Westerbeke, it ended up being too much head pressure because the owner never cleaned the heat exchanger. I haven't been around a NL in a very long time.

We noticed issues after installing 3 new sets on two different Hatts.

No, it happened in NYC. I popped it out while a mate ran slowly up the Hudson on 1 engine, popped in a Jabsco we had, and continued to do the entire Great Loop back to Fort Lauderdale without any impeller issues. The material the impeller was made out of was too pliable and sometimes they couldn't prime. They probably changed the formula since then.

The manual that came with new 15kw home back up gen, I believe with Kubota diesel, warned to NOT use synthetic as it may cause rings to not seat. Nothing said about using or not, after its early days so I've never used any.

That is what we concluded on ourselves. Break in oil.
Later Shibaura engines marinized by Luger, Onan and earlier Kubota engine manuals just spec CH or CK-4 oil.
Nothing in the owners manual says anything about synthetic.
One of the local reps got concerned when we were talking about oils in our new NL equipment. NL support called us the next day.

It is all CK-4 these days. I am a true believer that the synthetic oil works as good or better and more forgiving.

I also remember MAN engines specifying only certain synthetic oils from day one.