What type of lube is safest for male masterbation and will not damage sensitive skin etc with chemicals? are all water based lubes equally safe for prolong use every time i masterbate?

Any lubricant intended for sex is entirely safe. Many lotions also are entirely safe no matter how often or how long they are used. Avoid soap, shampoos, etc, which can be irritating especially if they get into the urethra.

Skin sensitivity can vary. So whatever lubricant does not irritate your skin is best. Water based lubricants have the advantage of being able to be washed off a lot more easily