My s40 has 145k, was thinking of getting a TerraClean. Costs about £90.

Anyone get any views? Maybe I should get a gas analsysis first?

Do a compression check if all OK and it's going well don't waste your money. Todays fuels don't cause carbon to build up as was the case years ago.

Agreed,

I notice that this additive has never had a bad write up,or anyone say its not beneficial which makes me very sceptical about it (I do not agree with any additives anyway)

Usually you find an article about an additive which says it did not work properly as tried by a customer, but there is nothing but praise for it much the same as other additives advertised but without any bad comments

There also seems to be very little info of it apart from it works

Do a compression check if all OK and it's going well don't waste your money. Todays fuels don't cause carbon to build up as was the case years ago.

Really? Petrol / diesel fuels aren't hydrocarbons anymore then?

The much more precise nature of fuel regulation compared to years ago, clean burn and better quality fuels does mean that engines carbonise less than they used to, but they can and do still coke up. On a petrol it's easy to look inside with an endoscope. Less easy with a diesel.

I'd suggest spending that 90 quid buying Shell V Power instead for the next couple of years.