I am a DIYer who has a manual grease gun for the large 14 oz. tubes of grease. I notice when the gun sits up for a while the grease separates and then the next time you use it a thin oil leaks out. How can I avoid this leakage? I have been using high quality but non synthetic grease up til now. Which of these greases offered by AZ is the way to go? I see at Auto Zone Mobil One grease for 6.99 and Green Grease for 7.99.... A second problem is with the gun itself. When I clip it on the frease fitting, it stays on great. Then when I try to pull it off, it won't release the fitting I have to really twist and pull it hard to get it off. I feel like I am going to strip out the fitting. What is the best replacement for the gr. gun to have it stay on but not relaease ? It has the rubber hose attachment on it.