I'm changing the Pushrod Tube O-Rings and I was wondering if I should use some sealant on them, or lightly oil them, or leave dry. Please Advise.

The ones coming out have some chafing, some chunks out, and some sealant on them. Such is the GEX rebuild...

Only oil, in no way sealant. I usually install them (pushrod with o-ring assy.) with a twisting motion of the pushrod. Once in (o-rings) I like to slightly tap the pushrod with a same size socket just to be sure it's all the way in.

I hope it sounds clear?

You don't want to use RTV, but a small amount of Locktite 565 applied just prior to installation helps lubricate and seal the push rod tube O rings. This is a Jake Raby tip that really works great.

Do a search on push rod tube seals, or tube seals. There's a few things you don't want to do.

Make sure the bores are clean and smooth without any scoring, any deep scratches or gouges can cause leaks.

Make sure you get the retaining wire clip in correctly, if you do it wrong and it rubs the push rod, it will cut it in two.

I see that GEX uses a mixture of seals ... wonder if they are left over from core engines?

Yea, it looks like 3 different colors of o-rings.