OK, so I am finally doing some 'housecleaning' under the hood of my '94 Olds LSS w 3800.

My brake fluid was low, so I filled it to the seam with DOT3- I am assuming that the seam is the fill line??? Also, the fluid in there was pretty dirty-looking.

I was giving the brake vac lines a once over and I noticed that there are 3 short lines that need immediate replacement - they are dry-rotting/cracking. 2 of the 3 are U-shaped and stacked atop each other.

I had the car idling in park (while checking AT fluid). The top U-shape vac line was 'collapsed'; the bottom one felt like it had air coursing through it. Is this normal for idling in park, or is the collapsed line indicative of a bigger problem?

Thanks!

If the hose has collapsed then it'* shot, just replace it.

The more I looked, the more rotten, gummy hoses. Plus the heater bypass valve is toast, getting a new one tomorrow. Will replacing these hoses help the performance any, or are these lines only put in use when the heater is on?

The only improvement you will notice would be any vacuum leaks that were caused by these hoses. That is not counting the effects of proper vacuum getting to the equipment now.