II was told that once synthetic oil has bee used in an engine , is it wrong to switch back to regular oil for subsequent oil changes. Can anyone tell me if this is correct, and if so why?
You can switch back and forth without a problem. Just remember that standard oil requires more frequent oil changes. Toyota now only uses synthetic.
As long as your manufacturer allows regular (check your owner’s manual) you may switch back & forth to your heart’s content. You may even mix them, or buy them premised (called “blended”).
Chemically, synthetic and regular oil are the same stuff. The only difference is in the amount of purity and the consistence of the molecule size.
When synth oils were first introduced many years ago, there was a problem with them causing seals to shrink. This led to oil leaks, and urban legends about older, or broken-in engines not able to use synth oils. Since then the seal shrink issue has been fixed and synth oil can be used anywhere.
Depends. Ur car MAY require a viscosity that is syn oil only. Like 0-20.