What's the real skinny on oil?

[Gramps]

I have heard numerous people say once you put synthetic in your motor, you can't go back to regular motor oil. Others have told me it makes no difference. So what's the real deal?

[vitalidle]

Sure you can switch back and forth just don't mix dino with synthetic

[NavyRedneck]

I'm not sure about diesels but I know it's bad to shift a high mileage gas engine over to synthetic. This is widely argued but in my experience I've had two engines start leaking at the seals. Both were over 90k miles.

If someone has an opinion about shifting a 230k mile diesel over to synthetic I'd like to hear it...

[CSIPSD]

Go for it... Switch back and forth, to and fro... it makes no differance.

[skip97IH]

I changed my '97 7.3L PSD no leaks 180,xxx
'96 5.7 K1500 no leaks 210,xxx
'89 5.0 camaro no leaks 120,xxx

I would say go for it

[NavyRedneck]

The ones that leaked:

2000 Toyota Sienna with 90k began leaking from valve cover. I switched it back to dino and the leaks stopped. I love this van. It's always had 3k oil changes and now at 110k, even when I pull the dipstick at 3k on the oil the oil looks as clean as brand new.

1999 Toyota Corolla with 130k began leaking from valve cover and something else that I can't remember. It was pretty significant, though, as it made a very clean engine look really oily. The reason for this was the detergents in the synthetic oil cleaned up the seals which had been 'sealed' from oil by all the deposits. Once they saw oil again the cracks that were there (but sealed) now started leaking. I switched it back to a high mileage dino oil but sold it before I could get much more data.


I will switch my 7.3 sometime before winter to synthetic, then. I definitely want the added protection from a synthetic oil before I head to New England for the winter.

[sirnunya]

maybe its a yota thing. these 7.3's can run on whale oil



jk

[scagle1]

My understanding is it does no harm to switch but that you need to keep an eye on it afterwards and if it is burning or leaking than you need to switch back to regular.

[cesspool]

Originally Posted by NavyRedneck

I'm not sure about diesels but I know it's bad to shift a high mileage gas engine over to synthetic. This is widely argued but in my experience I've had two engines start leaking at the seals. Both were over 90k miles.

If someone has an opinion about shifting a 230k mile diesel over to synthetic I'd like to hear it...

the leaks were because the synthetic cleaned the gunk out. the l;eaks were there, they were just clogged up.

[cesspool]

Originally Posted by Gramps

I have heard numerous people say once you put synthetic in your motor, you can't go back to regular motor oil. Others have told me it makes no difference. So what's the real deal?

switching doesn't hurt, like others had said. the only thing I would do is try to stay with a CI-4+ oil as opposed to CJ-4.

any particular reason why you want to switch?