I have been running fully synthetic Castrol EDGE 5W40 in my 3.5 V6 Gen 3 pajero for about 10k km (or 350 engine hours) and its time for an oil change with filter. Now, do I stick with Castrol EDGE or do I change to delo 400 multigrade? I have heard/read that Castrol sludges up in the motor, or is that only the normal Castrol mineral oils and not the fully synthetics??
If I do change, do I flush with some cheaper oil and then put the delo in? Or do I flush with delo, or do I do a straight change? Or is it not worth the hassles down the line.... I have read somewhere that switching from fully synthetic to mineral can cause problems. I have been running with delo 400 Multigrade in my corsa 1.4 club, and have been very impressed with how smooth the engine runs after the change.
Any advise would be appreciated!!