Trig 0 Posted August 26, 2005 Need to top up my engine oil (94 VR6, 125k) but I don't know what grade of oil is already in there. I want to use Castrol GTX magnatec 15w 40 (did a search), is it ok to use this not knowing what oil is already in there? ...or I need to do a complete oil change bearing in mind it was only serviced 10 weeks ago? A bit of a newbie question, I know. Quote Share this post Link to post Share on other sites
cymru-corrado 0 Posted August 26, 2005 had my oil changed yesterday went for safe option and had it drained flushed and re-filled.running nice and smooth now Quote Share this post Link to post Share on other sites
stevemac 0 Posted August 26, 2005 triggermyson, Essentially, it makes not much difference which oil you top-up with. So long as the grade is either 10w40 or 15w40. Contrary to popular opinion - mineral, semi synthetic & fully synthetic all mix together with no adverse effects. I would just top it up with 10w40 semi synthetic. Quote Share this post Link to post Share on other sites
