Want product that gives hair weight

Well, that is the new fad with the silicone conditioners, to have a deep conditioner than doesn't add weight because the one thing people always complained about was after a few uses, their hair going "limp".  I still have an old bottle of pantene conditioner full of the old formula, that definitely weighs down and makes my hair limp...I haven't bought a new bottle in years, so I don't know if they've changed their formula as well, but you could try pantene.  Its really only 4 uses with the stuff that my hair is so weighed down it looks bad.  If the new stuff doesn't do it, you might try the discount stores to see if they have any old pantene (trust me, there are so many preservatives in it, that brand doesn't ever go bad like some do!).  Be aware that if you use silicones to weigh down your hair, it is a good idea to strip them off every couple of months because they build up and make a coat around the hair shaft.  Over time the coat can start to look dull, then crack and break your hair off with it, leaving you with split, dried out hair.  Removing the old 'cone coat every 2 months with a clarifying shampoo then replacing with a new coat will keep your hair from getting buildup damage.  (Clarifying shampoo should not be used more frequently than that, especially since you want to keep a weight coat on yours - it will make your hair feel like straw when you use it, but 2 coats of a 'cone conditioner after that will fix it right up).

If you don't wind up finding a silicone conditioner that adds weight, you can try oil.  Use one or two drops of oil on dry hair, from the ears down only, brush it through to spread it.  It should not look greasy or get oil on your clothes, if it does you used too much, wash it out and use less next time.  Good ones are jojoba oil, coconut, or you can even try olive oil from the grocery just to see if it works for you.

Most conditioners do have silicones, I've found pantene to be the heaviest of all I've tried, (but again that's that old formula).  As a general rule, look for words in the ingredients that end in "cone" or "one", and the higher up they are in the ingredients, the more of it there is in the bottle. 

If you do have bad buildup, you may be in for a shock when you use the clarifying shampoo, I just want to warn you beforehand.  It will make your hair feel very brittle, and you may actually see more breakage - but you may as well do it anyway because your hair breakage can't be prevented if you've got a buildup coat that is going to keep breaking off on its own.  Just be prepared to do a heavy moisturizing after you do your clarifying wash....you can even use mayonnaise (fatty one, not the fat free stuff, and not miracle whip) and leave it on your hair for an hour, then wash it out with a regular shampoo.  Its eggs and oils are an excellent moisturizer....then even if you do use it, I'd still condition once or twice after that to get your hair past that stripped and brittle clarified state. 

What you say about oil sounds like your hair is super thirsty.  I think the heat is probably more the cause of your trouble than the silicone buildup, as you've said.  If its really that dry, there may not be too much you can do other than keeping a fresh coat of 'cones' on it to keep it looking good until healthier hair grows out.