Hi, Could someone explain please what the rev counter colours mean and what order they come in on the dial and do any of the colours overlap? I’ve searched online and was surprised that I couldn’t find a full explanation anywhere. Thanks.
The green bit is where the office bod, who has never been near a truck, has been told to tell you to keep it in. 
The Blue bit is where you’ll get a snotty letter from the office bod for wasting fuel, even though it says in the manual to use it for engine braking and doesn’t use fuel at that point. 
The Red bit is the bit you use when the office bod, his boss and the whole dam company has [zb] you off and you’ve decided to leave in a blaze of glory. 
Thanks for the link Rog. I found it before I’d posted and the video is really quite interesting and useful. The voiceover is definitely from another age when they used to do things like that really well. The age of public information films, etc.
Haha Muckles - that is hilarious! What about amber? Can you remember what order the four colours go in? I did clock it once but it didn’t make any sense to me at all and I think because I never understood it, it never went into my brain.
I would assume if all four colours appeared then it would go green, blue, amber and red. Cant remember ever seeing one like that myself but theres always some weirdness out there…looks at Scania. 
Like the description of the red line. Did it once accidently with a very strange gearbox, and boy did it dislike me afterwards.
Thanks Trev! I’ve got a feeling in a Renault I’ve seen green → amber → blue → red. It was something odd as I remember at the time thinking it didn’t make any sense to me. Maybe there isn’t a standard then by the sounds of it. I never really thought of it too much since then but am revising for a driver assessment here - mocktheorytest.com/highway-code/heavy_vehicle/ - and a question came up on the colours and it got me wondering again…
A couple of times a year I take my car very near to the red line in third on a quiet stretch of dual carriageway. I put some engine cleaner in the fuel first. A whole load of crap comes out the back. The engine seems happier after tho. But I won’t be trying it in a truck