Will switching from fully synthetic to regular motor oil cause any engine problems?

All the oil companies say that their oil is fully compatible. So it should be no problem switch back and forth. And I have with no problem.





The problem isn't the compatibility of oils (You could even mix some syn with some conventional oil). The problem is that synthetic is ';better'; oil in that it can handle higher temperature oil (and it resists thermal breakdown). So if you have high temperature engine (ex: My Audi A4 1.8 TURBO), the it is advisable to stay synthetic.


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Very rarely but sometime the problem occurs going from conventional oil to synthetic oil. The synthetic oil can loose up stuck gunk (oil sludge). And those newly loosened gunk can start traveling around your engine until it gets stuck somewhere else (like in your oil filter).


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Conclusion: the oils are fully compatible. If you have fairly clean engine, you should be fine switching back and forth.Will switching from fully synthetic to regular motor oil cause any engine problems?
YES if you have a supercharged turbocharged or anything other than a 4 cylinder or non-performance tuned v-6. You should step it down to a synthetic blend before going to just plain motor oil (my advice).Will switching from fully synthetic to regular motor oil cause any engine problems?
Synthetic oils have wetting agents which help the oil get into places a little easier, but on some older engines with questinable seals, sometimes leaks occur. Not to worry though, changing back to dyno oils usually stop the leak. Otherwise, synthetics are usually superior with engine protection.