Sorry if a silly question. For this large capacitor in my stock 95 Pioneer head unit, is this leaking or some kind of factory applied adhesive? It doesn’t look like leaking based on other leaking capacitors I’ve replaced but wanted a second opinion I guess.

Second question would be, if I am going to solder in an aux cable, should I replace this larger capacitor preventatively if this isn’t a leak or if no symptoms leave it alone?

 

that can only be a leaking electrolytic capacitor, as they are soldered in, not glued.
if you're confident in your soldering skills, and found the exact same replacement cap, then replace it! i'm not sure how accessible the bottom solder pads are in the headunit.

 

Thank you. I asked someone who has professionally rebuilt Lexus ECUs for a long time and he thinks it’s glue. The AI models I asked also thought glue. I guess sometimes glue was used to keep them from moving if in an area where rattling might crack a solder joint. However, I’m open to opinions and I appreciate your response. I am leaning towards it being glue but I have no idea for certain.

 

hmm never thought about gluing them down to prevent excessive wear on the solder pad. could very well be plausible!
if you're ECU rebuilder sees glue being used in the past, then it's more likely that - plus it's performing just fine so why fix what's not broken!

 

Just adding my 2 cents here. I am also pretty sure that is glue

When I took apart my radio in my 2001 Camry, I found the large capacitors were also glued on. I had to replace one to fix a parasitic drain issue

The glue was whiter in that car, but I imagine it yellows over time with heat.

I am pretty sure the glue is there to account for vibrations, but I am not sure.

 

Pioneer used to use some glue for bonding larger parts. Sometimes it causes current leaking problem when aged as is posted here. Later Pioneer has changed the glue for a better reliability.