Hi , I have posted a similar post but not sure really got to the bottom of things..The HTHS in Amsoil Sig 5w30 is only 3.1,( i have been using this oil )
but I wanted more engine wear protection so I have now put Amsoil Sig 0w40 with HTHS 3.7 into the car ....its a 2010 petrol 1.4 i-vtec Honda civic in the UK its not a Direct injection engine has no turbo but of course has a CAT ..I just wanted to be assured that I'm not damaging the CAT with this oil , I would assume it has a higher ZDDP than the 5w30 Amsoil Sig oil ( its difficult to find this info ) ,, I know many will say use the Amsoil European formula ,, but the car has done less than 70,000 mls and burns virtually no oil , so I'm hoping that even if the ZDDP is higher in the 0w40 I will not harm the CAT
but I wanted more engine wear protection so I have now put Amsoil Sig 0w40 with HTHS 3.7 into the car ....its a 2010 petrol 1.4 i-vtec Honda civic in the UK its not a Direct injection engine has no turbo but of course has a CAT ..I just wanted to be assured that I'm not damaging the CAT with this oil , I would assume it has a higher ZDDP than the 5w30 Amsoil Sig oil ( its difficult to find this info ) ,, I know many will say use the Amsoil European formula ,, but the car has done less than 70,000 mls and burns virtually no oil , so I'm hoping that even if the ZDDP is higher in the 0w40 I will not harm the CAT