PerfMad

What @DeeJay said...yes,..traditionally (and even with other liquids) yellowness can mean higher sulfur content. However, these days it is not always the case because of chemical additives, etc... 

Is there any independent body that does random fuel tests on a periodic basis ?

By the way...a few days ago Toyota and ENEOS demo'd their synthetic eFUEL petrol. They seem quite positive about it and hope that it can be commercialized in the "near future" but not the immediate future (hard to translate it in to English). Whilst Toyota's new guy is pushing BEVs Toyota doesn't seem to be totally giving up on gasoline (hybrid?) powered cars as well. Has nothing to do with diesel purity...it just came back in to my head whilst thinking about dirty diesel.

@Dee Jay wish i could measure it  but we have to rely on what ever we get assuming its the best.

@iRage does these addictive's can have a smell too?

@PerfMad I don't think they will sell something inferior because if so it would lead to DPF issues in majority of the vehicles which require SD and they would be aware of the consequences..

Here, you will find the spec sheet from Ceypetco for Super Diesel and please do note the row 'Colour ASTM', the 'Method' for that and the 'Specification' of that.

IOC XtraMile has a slightly less colour value in the specification which is based on the same colour grading standard, if you check the specification from here.

However, when you compare the Suphur content of both products in the specification you can see that XtraMile has more Sulphur content than Super Diesel. The Sulphur measurement however, is not measured using the same scale in both products though. It seems IOC uses an old standard to measure the sulphur content. 

You can read about the Sulphur tests employed by both vendors here. 

So, don't worry about Sulphur content just because one product has a darker yellow shade than the other  IOC however, should update their website if they have a better XtraMile Diesel on sale at the moment because their site only has a 2013 specification while Ceypetco has a 2022 December specification.