If I am not mistaken, you should not be using lithium grease on the rails. The reason being is that dirt, dust, etc will stick to the grease. RV places sell a dry lube for slide outs. Not expensive but not real cheap either(but what is when it comes to RV's). That's what I use. I go through about a can a year. I think it is under $15. Hopefully someone else will chime in on using lithium grease. I remember my dealer saying no to it though.