Is too much oil, (I'm talking 10mm above the max on the dipstick) detrimentle anyway to the engine?

10mm, so 1 cm? no i dont think that will be detrimental. The oil in my car is like that atm i believe. When you hit like 5 - 10 cm above, then it can be bad

depends really - does your motor chew through the oil in your car a lot?
or does it never seem to 'use' (burn etc) any of it out?

if the car uses the oil, then that will be fine having it a little bit above max as its only gunna loose it

if it doesnt, then it would be a worry if you had overfilled it by a LOT - overfilling can cause areation (spelling) of the oil, which will result in the oil pressure in your car being no-exsistant which can lead to problems with your motor.

being its only a little overfull, dont stress!

from what i know 10mm sounds like close to 1 litre above, id be thinking about draining it a bit

The magna doesn't seem to be using any oil which is a bit of a change because my VR4 does a little.
I drained a bit out of the magna just incase and the 10mm equated to about
250mls.
I heard the same thing about the oil pressure issue, but I figure you would have to have well over 10mm higher on the dipstick.

Cheers for the replies guys

250ml is less than i guessed, but better to be safe then sorry i suppose

while motor is cold

get an oil drain container

undo the sump bolt
let some oil out

retighten the sump bolt

top up to correct level

If you are according to dip stick level yes you may have topped up a little too much, and depending the TYPE of oil it may lower your engine performance.

I am only saying this because according to the recommended Engine type e.g 2.4L requires only 4.3l of engine oil, and when that amount is poured into my engine is not indicating at MAX for my dip stick. I normally top up a bit more makking near the full mark.

If is way too much loosen the nut to release some oil and check the oil sump level again.