The colour of plugs when you take them out.

[DaveT]

I currently use Champion L86C in my high compression head and I was going to order a set of NGK B5HS (4210) as recommended by Graham Honnor.
 
So I emailed The Green Spark Plug Co. and told them I was using L86C and wanted a hotter plug to reduce oiling.
 
They replied with details of NGK B4H (4110) £2.15 whereas the NGK B5HS (4210) is £1.69.
 
So is there a ranges of hotter spark plugs as I also found NGK B6HS (4510) £1.38.
 
Also the NGK Copper Core Spark Plug BP5S (3011) is listed £1.79
 
I’m now confused as to which I should fit I as I don’t want to melt the pistons as I recently did on our 2015 Ford Kuga 1.5L Ecoboost with only 15000 on the clock but that’s another story, but I did get my money back from Ford.
 
I Think I’ll phone them tomorrow and try to establish the difference in plugs that dimensionally are all identical. Unless someone can answer this query