A friend of mine has a 2002 Honda Insight (hybrid) that has a rear main leaking. He is currently doing an Auto-Rx clean cycle using the OEM specified 0w-20 oil that is only available as a full synthetic. Is there any reason to believe that switching to a 5w-20 convention would do harm on a temporary or permanent basis? I know the economy is likely to be reduced and because thee gas engine isn't running constantly it takes long to reach operating temperatures, but that's different than being damaging to the motor. Auto-Rx recommends conventional even after the treatment.
Thoughts?
Thoughts?