concerned.

[Nkerridge]

In 2 days time im off to france on a 1000k round trip in my 3.0 ssrv.
i have had a full service and have replaced my radiator with a MILNERS
radiator As the old one could not be trusted, first real trip down the A12
80mph and grey smoke, eased back and no problemns, back to 80mph, and grey
smoke ?? WHERE DO I START.

[TonyN]

check the oil isn't over filled, check the fuel filter is tight, air filter blocked? could be lots of other things.

check the inlet manifold for junk from the EGR or the intake pipe for oil from crankcase pressure.

Could it be you've just not noticed it before, and has always do it under load, try a bottle of redex to clean the injectors and drip some down the intake to clean the intake.