I had some GT enth that was very painful and got me sick every shot. I just switched to QV enth in a 50ml bottle and I have no issues at all. None of my QV stuff has ever been very painful. Also, I have found that what is painful in my quad is painful in my glute so there is not much of an advantage there unless you rather train legs with a sore glute than sore quad. A few things you can do is:
1. Try the steril oil mentioned, I never has but it sounds like it works.
2. Make sure you are using a new pin, don't use the same one you stick in the bottle.
3. Inject slow
4. Massage the injection site really good. For 5-10 minutes.