for 2 years now i've been using 20w/50 oil in my nova and i've recently been having a few problems which are sorted now due to a engine cleaning agent that a garage added to my oil. The garage asked me what type of oil i was using and i told them 20w/50 and they said i was using too thick an oil i should be using 10w/40 for my hydraulics.
I read the guide in the total vauxhall magazine on oils and what is suitable and i'm still a little confused on which to use.
One part says it's safe to use 10w/40 on cars made in the 80's and 90's but then at another part it says if used on a car that was made in the 80's it would drink the stuff.
I dont want to put 20w/50 back into the car incase it's too thick and this is how i was getting my problems.
i'm doing an oil change in a few hours and i have 10w/40 oil sitting here waiting to replace my 20w/50.
please can someone advise me on what oil i should be using and is 10w/40 going to be ok.