I am using fully Synthetic oil now but I want use back carstrol GTX oil .the question is If i just change the oil Is it still have some Synthetic oil left in oil cooler(I am not sure ).If it is then after mixed GTX oil and Synthetic oil any problem??

 

You will still have some oil left in cooler unless you drain that too. I wouldn't worry about it doing any damage. And it will probably be so little you won't know the difference

 

thanks reply

 

yeah there's no real damage that would occur. There's never gonna be anyway to get ALL the oil out of an engine anyways. I suppose you could flush it like a transmission but jeez...

 

No problem mixing ,What do you think parasynthetic is that you buy off the shelf ? It is a mix . Castrol in the gray bottle . The black bottle is full syn, GTX is not syn .

 

I always thought the best way to change your oil to non-synthetic was to do an oil change (you don't need to change your filter) drive it around for a few hundred miles, and then change it again along with the filter. That would definitely dilute the amount of synthetic left in your system and "flush" whatever is left out with the latter oil change. It's just an extra 4 quarts of oil....