Someone told me that once you start with synthetic oil you cannot go back to Dino Oil. Then why do they make blends??? What could synthetic oil do to an engine to make it use oil? I think that someone was wrong. What say U RS Clinic?
I say that comming from the experience of over 40yrs wrenching motorcycles/cars/Classic muscle cars including rebuilding motors along with also researching oil for another forum (Team Chevelle) over the past 4.5-5yrs due to issues with premature failure of high perf aftermarket Flat Tappet cams used in classic muscle car motors thats related to low zddp lvls in most but not all of motor oils mfg'd today.
I bothered to tell you that so you would know my $.02 was comming for many yrs of 1st hand exp and also from some yrs researching oil too so you know it's not just an opinion i obtained from changing oil & spark plugs on Saturday's.
One of the issues going back & forth between std dino & syn is that older/original motors like for example in a 40 yr old muscle car have a tendency to leak syn oil where std dino doesn loeak or leaks very little std dino .
It's partially because that older motor tech doesnt have as good sealing tech like stamped steel oil pan/valve covers vs todays more ridiged cats AL oil pans/v-covers etc with better gasket tech too.
But it's also because syn oil has a smaller mollecules on a mollecular lvl then std dino does so smaller mollecules can leak more easily then larger molecules.
So with that in mind if you have a tired motor with poor ring seal and also worn v-seals & guides it will liely use/burn more syn oil then std dino of same visc.
Lastly,some older generation motors have issues with ring not breaking in properly/poor ring seal with syn oil due to it being slicker/more slippery then your avg std dino which isnt always the case with that app but can be.
But most if not all motors mfg'd these days are designed to breakin & run on syn oil so syn oil isn't an issue with them at all.