Synthetic Oil...

[monty]

Is it true once you put it in your car, you should not go back to regular?

[Pinepig]

False

[gearheadE30]

I've heard both but never seen conclusive evidence either way.

[backtrail69]

Generally they recommend to not run syn when you have an older engine with lots of deposits since it will clean them out with all the detergents it has and most likely will start leaking.

[e30 Luv]

Generally they recommend to not run syn when you have an older engine with lots of deposits since it will clean them out with all the detergents it has and most likely will start leaking.

This is what I have heard as well. Seems like no one can agree. I have heard switching from dino to syn back to dino is not recommended but never heard why. Then I heard from someone else that switching from dino to syn will cause leaks, but eventually they will clog up with new deposits. Everyone always considers this site: www.bobistheoilguy.com as the authority. But I have yet to read much on the site.

[dlmpsy]

My car has 207,000 miles, synthetic has been in it after about 35k. Oil is certified to meet certain standards, switching shouldn't hurt anything. Some people say they have more leaks going from a conventional oil to synthetic. From my non scientific observations, synthetic oil flows a lot better and if your seals or gaskets are marginal anyhow they may leak a bit. As far as gunk goes, if you have a lot of gunk in your motor then you already have a potential problem. LubroMoly makes various products to clean your motor internally, I wouldn't be scared to use them.