Installed Oil Cooler, how much extra oil to add?

Using a GPz oil pan and cooler/lines on my KZ750E2. Factory manual suggest the same oil fill on both the GPz and my KZ. Seems to me there is a fair bit of oil that fills up the cooler system so shouldn't the GPz take more oil? I've got the oil fill at the very tip top of the sight glass for now but wondering what some of you other guys have done after adding an oil cooler?

Run the motor, leave overnight for the oil to settle then top up to the correct level in the sight window.
If the cooler has the fittings on the top then some oil will remain in the cooler giving slightly more oil capacity.
If the fittings are at the bottom then most of the oil will drain back to the sump.
Don't overfill the sump to compensate as it can blow oil seals, blow out of the breather or fill the airbox and get drawn in to the cylinders causing smoking and plug fouling etc.

It's an OEM cooler, so fittings are on the bottom. All the oil in the system will drain back (I think).

Running the bike with the same oil fill as before the cooler was installed means that the oil level in the sump while running will be reduced by the amount in the cooler. That's the question: is it okay to run the engine like this? Seems to me a better situation will have the oil level in the sump while running the same as before, not reduced.

Yes! it will be just fine.
The GPZ runs like that with no problems .
The amount of oil carried in the cooler and pipes when running is minimal and won't cause any sort of oil shortage in the sump.

zed1015 wrote: Yes! it will be just fine.
The GPZ runs like that with no problems .
The amount of oil carried in the cooler and pipes when running is minimal and won't cause any sort of oil shortage in the sump.

yes it can't be more then a few ounces of extra oil.

zed1015 wrote: Run the motor, leave overnight for the oil to settle then top up to the correct level in the sight window.
If the cooler has the fittings on the top then some oil will remain in the cooler giving slightly more oil capacity.
If the fittings are at the bottom then most of the oil will drain back to the sump.
Don't overfill the sump to compensate as it can blow oil seals, blow out of the breather or fill the airbox and get drawn in to the cylinders causing smoking and plug fouling etc.

Thats pretty mch what I do when I change the oil. I keep the oil level in the upper half of the oil window. Fill, run, let settle and top up if necessary next day. Dont over fill
I have an after market Derale Oil cooler which was on the bike when I bought it 12 years ago and have had no problems doing it that way.



I am really looking forward to seeing photos of your finished bike Nessism. You seem to have put a really thorough aamount of painstaking work into it and it sounds like it's almost ready to fire up and ride