Fully to semi synthetic oil - cars

[sidetrack]

I have heard once you use fully synthetic you cant go back to semi synthetic is this true ? Our car's diesel's service was always with Mobil 1 but now since it's older and the current place is asking ridiculous money for a service I got a price for Shell Helix HX7 for half the price. It's semi synthetic.

 

[the_BOBNOB]

 

[Vintage_Mania]

 

[sidetrack]

 

[2StrokeDan]

 

[JesseH]

 

[Slainte Mhaith]

 

[2StrokeDan]

 

[jaybiker]

 

[Oubones]