Just did my oil and after i finished refilling the engine with the new stuff when i glanced at the bottle and noticed it was 5W30...

First thought was crap I dont wanna have to buy another bottle and redo it... then I considered that being winter, the temperature might actually suit the oil nicely. took the car for a drive with the new stuff in and it drove fantastically! The idle was a lot smoother than the usual magna idle and it seemed a bit more gutsy.

any experienced opinions on whether itll be fine to keep in there or not?

Just did my oil and after i finished refilling the engine with the new stuff when i glanced at the bottle and noticed it was 5W30...

First thought was crap I dont wanna have to buy another bottle and redo it... then I considered that being winter, the temperature might actually suit the oil nicely. took the car for a drive with the new stuff in and it drove fantastically! The idle was a lot smoother than the usual magna idle and it seemed a bit more gutsy.

any experienced opinions on whether itll be fine to keep in there or not?

should not be a problem it is thinner just be aware that lifter noise can become an issue ( my 380 was running 5W-30)
What brand oil did you use?
After I ran the 5W-30 I went a high Detergent 10W-40 Shell Helix ultra before changing it to Mobil 1 5W-50 and is singing nicely with NO lifter noise

I used 5-30w in the old 3.5l, no lifter noise. Im in NZ though, so it may be a different story if you live in hotter climate.

That oil will be fine......theres plenty of info on this if you search!

cheers guys, great relief! i could have sworn someone posted something about using 98RON... must be my imagination, weird.

I used Valvoline Semi-synth