good day, I decided to start this topic so we newbies can learn one or two thing from gurus in the house and also experienced individuals on this matter.

1. I was wondering how one can revert back to recommended engine oil usage from long time use of non recommended one example a car is supposed to utilize 5W20 and the owner was using 20w50, so the owner decides to revert back to recommended how do you do it without damaging the engine itself.

2. Also how long is it too late to revert back to recommended how long would the unrecommended engine oil be used before it will be too late to revert back.

thank you

nurey:
good day, I decided to start this topic so we newbies can learn one or two thing from gurus in the house and also experienced individuals on this matter.

1. I was wondering how one can revert back to recommended engine oil usage from long time use of non recommended one example a car is supposed to utilize 5W20 and the owner was using 20w50, so the owner decides to revert back to recommended how do you do it without damaging the engine itself.

2. Also how long is it too late to revert back to recommended how long would the unrecommended engine oil be used before it will be too late to revert back.

thank you

I always advice my client to try the recommended oil if the years of using the wrong oil is nt more than 2 years and monitor for any abnormalities e.g oil shortage ,white smoke , performance issue,etc and to revert to your wrong oil if any of these issue come around.
Though I change my corolla 2005 engine oil to the recommended oil 5w30 after like 4 years of using 20w50 and the change was seamless with very good performance and good fuel mileage to show for it .

diesel treatment then drain.... and put in your recommended oil...