Is there ANY advantage to vacuum hubs?

The standard system is a double isolation system where the transfer box isolates the front drive so propshaft, diff and half shafts and then the hubs isolate the wheels meaning the in 4x2 the front drive line is static not being driven by either the engine or the front wheels. Allegedly this is to save wear and tear and supposedly fuel. You will be lucky to be able to measure any difference over the lifetime of the car. With manual hubs yes you have to get out of the car to engage them but it is perfectly safe to engage them once at the start of a run on the lanes or the pay and play and then disengage them at the end of the day before going home, but then using the 4x4 selection buttons as needed throughout the day and not engage and disengage the hubs every time the terrain changes. In reality many people with manual hubs leave them locked all the time and don't suffer any more failure than those who switch them as needed. Also the other major factor is that you can leave the hubs disengaged and then select 4x4lo meaning you have a simple way of using the low gearing on high traction surfaces without doing the nasty to the transfer box which is useful if you are manoeuvring a trailer creeping in a traffic jam.

Have a quick look to see if there's anything obvious. If not, get manual hubs to keep your sanity. Trying to find the fault can be a nightmare.

Have a look through the posts from the last few weeks as there's one on how to block the vacuum pipes to stop the light flashing.

I have fixed hubs, which is no different from leaving manual hubs in locked all the time.

As for the grease thickening up, this isn't an issue in the UK. Grease will harden over time anywhere. A regrease every 5 years is not much hassle, or less often.

Or fix your ones as per my guide at the top of the technical section.

Kirkynut

My normal black tops are aluminium outers with plastic internal switching mechanisms. The actual locking components seem to be sintered powdered metal. My last set gave 5 years of service before a bearing surface failed. The polished aluminium will stay shiny until the first exposure to road salt then it dulls within the month.