Update to 4.0?

[Smirnyi]

Hello, Im trying to find out if I should update my iPhone 3GS 3.1.3 to 4.0 via iTunes. I JB my phone with Spirit and unlocked with ultrasn0w.
I guess my question is: is it will be safe to update my phone to 4.0 os?
Thanks

[ianbroste]

You can update to iOS 4 but unless your phone was jailbroke on an earlier firmware (3.1.2, 3.1, 3.0) and your SHSH blobs are saved in Cydia, you cannot jailbreak iOS 4.

[Smirnyi]

NO, I JB MY PHONE ON 3.1.3, so I can to update to 4.0. Is this correct? Just want to be sure...
Thank you

[iYeow]

NO, I JB MY PHONE ON 3.1.3, so I can to update to 4.0. Is this correct? Just want to be sure...
Thank you

No, you can't jailbreak iOS 4.0 if you have either one of the following :
Jailbroken by Spirit
I have the new bootrom

[Smirnyi]

I think I asked my question incorrectly.... I update my Jailbroken (SPIRIT) and Unlocked (ULTRASN0W) iPhone 3 GS 3.1.3 to 4.0 and.... My phone got back to APPLE version (NOT jailbroken and NOT unlocked). Well, I accept my (DUMMY MISTAKE). Have to wait for LIMERA1N? I don't know... But anyway, thanks for responses.

[ianbroste]

Like I said originally. If your phone was jailbroken on an earlier firmware (3.1.2) in the past and you saved your shsh blobs you can jailbreak it on iOS 4

[Smirnyi]

Sorry for dumb question, but not for beeing jailbracke on 3.1.3... Correct? Thank you.

[ianbroste]

If it was previously jailbroke on 3.1.2 you can downgrade to 3.1.2 and then update to iOS 4 and be able to jailbreak iOS 4

[Smirnyi]

I'm sorry, did you mean If it was previously jailbroke on 3.1.3, (not 3.1.2 (i think you mistyped it)). Then you can downgrade it to 3.1.2 and then update to iOS 4 and be able to jailbreak iOS 4. Correct? Sorry for my possible misunderstanding...

[iYeow]

You must be confused. In order to jailbreak at 4.0 , you must use restore to a cfw of 4.0.
In order to do that, you must be jailbroken at less than 4.0. The jailbreak can be any jailbreak other than spirit. New bootrom cannot accept custom firmware, only old bootrom can do that.
There is only one jailbreak at 3.1.3 , which is Spirit. So, jailbreaking at 3.1.3 is out of the question to use cfw.
At version 3.1.2, you have the option, spirit, Blackra1n or Redsn0w. You can either jailbreak 3.1.2 with Blackr1n or Redsn0w. And if you jailbreak with these tool is untethered, then you can use a custom firmware of iOS 4.0 to restore.