If you need a pint of hydraulic fluid every oil change I`m afraid your transfer case may be going south. I just posted this on another thread:
"The 4-Matic transfer case tends to develop an internal leak from the hydraulic fluid side to the ATF side after 100 k or so. This leads to failure of the TC and a $3K to $5K R&R. I'm changing the TC ATF at least once a year and check for contamination. Inexpensive peace of mind. Aslo, check your hydraulic fluid level regularly. If you notice it going down change your TC ATF more often; e.g. every oil change. If (when) the TC fails you can avoid the expensive R&R by putting the 4-Matic in test mode and drive it as a 2WD. However I believe that the self leveling feature may not work anymore."
'93 300E 4Matic
'98 Nissan Altima
'00 Yamaha Road Star Silverado