i was wondering what the exact amount of oil to put in my 68 z28 with filter? i know this seams like a dumb question but my dipstick always reads overfull. i believe it has the correct indicator green tip?

If it's a stock pan, including the filter it should hold 5 qts. todays filters are smaller but shouldn't matter that much...

I believe the correct tip color for the Z is grey. I have the green tip one and that's what all the repro ones are and I heard not technically correct.

Just going by memory, so I could be wrong...

There are two different length green-tip dipsticks. One around 17", the other around 22".

I don't know if the 68 s are different, and it might also depend on the dipstick tube that you have. For 69 and 70 the shorter one is correct.

As mentioned, 5 qts w/filter should be good.