I use Smith and Allan for most of my fluids as they are well known in enthusiast communities for producing quality fluids from Shell base oils due to being one of official Shell UK distributors. I know they have been working on their C1 oil formulation since last year and I notice they have now launched it on their website.

https://www.smithandallan.com/products/pas...otor-oil-/

I appreciate some prefer to stick with the big brand names but for those that believe 'if it meets the spec, it meets the spec' then this is the best value source of C1 oil as far as I am aware.

Hope this helps  Kev

MY2014 L405 RR Vogue SE 4.4 SDV8 in Corris Grey
MY2010 L320 RRS HSE 3.0 TDV6 in Stornoway Grey