Synthetic oil was used the last 3 times or so on my 99 138k mile maxima. Yesterday, I went to get another oil change, but failed to mention synthetic, so they did regular.

Am I screwed?

Thanks.
Dan

 

not screwed at all, but it is usually ideal to stick with one type. Regular or Syn.

 

Once you switch to synthetic oil you MUST ALWAYS use synthetic. Synthetic oils have an additive in them that will cause your engine seals to swell. If you change back to regular oil those seals will begin to shrink and your engine will soon begin to leak oil like mad. Give it about 3-400 miles before you start to notice oil leaks. Another problem that can occur is that your compression will drop because you have created leaks in the engine. I would go back right away and have the oil dumped and get it replaced with synthetic. It may cost you some money now but it will cost you a whole lot more in the future if you don't have it done!!!!!!

 

if hes right id flush it pronto

 

really? wow i thought no harm was involved with switching back and forth?

 

it's not going to hurt anything to switch back. i wouldn't recommend doing it repeatedly, but you're not going to kill your engine or anything. some older syn oils had problems switching back and forth, but as long as you stick to the major brands, you'll be fine.

a better question is, why aren't you changing your own oil?

 

There isn't. You will be fine. The myth about once you switch to synthetic you must always use synthetic is just that, a myth. Run that oil for a regular change interval and then use synthetic again if you want.


Adam

 

LIAR!!!!
you'll be fine. Just switch back after 3k. Syn. cleans better, causing some older engine to leak by removing the grime that prevented already present leaks.

But he was already using Syn, so that doesn't even matter.

It is far better to top off with dino then drive around w/o enough oil until you find the Syn.

If this was a problem, Mobil 1 and others would require a "Syn Only" warning so this mishap wouldn't occur.