I am going to change the engine oil of my Mehran 2008. The mechanic has suggested Caltex Havoline 20w50, as summers are approaching I want to know if it is feasable to go with this oil? Previously I use Shell Helix 10-40 Yellow Packing. Also please suggest good brand of oil filter. I will be getting this oil change from Caltex F-6 Super Market so I am concerned about its reputation also in terms of getting a genuine product.
Moreover, i want to flush the engine before changing oil because the previous oil seems to have too much dirt in it. its just my personal thought. i consulted with the mechanic and he said you can pour any local oil for 1 or 2 minutes and keep the engine start and then take it out and it will work as a flush so i want to know if it is the right way or i should purchase any good brand engine flush? if yes then which one and from where?