Back in 2005, through to 2009, I ran a Vauxhall Omega B 2.5 V6. I also owned a 2.0 16 valve for a short while. I won’t go on here, about what a great car I personally think they are, but, I will share some links to various How To guides I compiled, way back when I owned the Omega.
Omega FAQs
My online forum name, was ‘Vectrolosys’. I contributed a fair amount, to the following FAQ thread.
https://www.vauxhallownersnetwork.co.uk/threads/omega-faqs-please-check-first.87821/
Omega How Tos, by Vectrolosys
Automatic Transmission Fluid and Filter change
Replacing the rear differential
https://www.vauxhallownersnetwork.co.uk/threads/replacing-the-rear-differential.150490/
Replacing the Omega V6 oil cooler (process is broadly similar for other applications of this engine)
Replacing the front suspension wishbones
https://www.vauxhallownersnetwork.co.uk/threads/replacing-the-wishbones.125043/
Replacing the heater bypass valve
https://www.vauxhallownersnetwork.co.uk/threads/replacing-the-heater-bypass-valve-2-5-and-3-0.89567/
Cleaning the PCV breather assembly on the V6
https://www.vauxhallownersnetwork.co.uk/threads/cleaning-the-breathers-on-the-v6.118814/
Link to the main FAQ
https://www.vauxhallownersnetwork.co.uk/forums/omega-how-to-and-faqs.82/