looking at buying a lower mileage 30k or less c5 and finding many sellers have not changed fluids in reccomended time frame (1 year). If a seller only changes oil say every 3k miles and this is a 2+ year time frame would this be a cause for concern with engine damage.
also seeing many with original dexcool after 11+ years understand not as critical and can be tested but oil advice would be appreciated.

 

Late last summer i bought a c5 vert put 300 miles on it and parked it in my garage for the winter. Spring finally was here so i thought i would do all the fluids because i wasn't sure it was ever done. Well now after doing that my rear-end has a couple of drops on the garage floor after going out for a cruise, which has not done that all winter in storage. I checked drain plug, it's tight, so i guess the seals are going to be replaced sooner or later. I wonder if changing the rear-end fluid may have caused it? Oh well lucky me. Car has 11k on it. I guess the seals dried out because they could not be worn out with that little bit of miles.

 

Hence the potential problem with low-mileage cars that sat for extended periods. Letting synthetic oil sit is certainly not as bad as doing the same with regular oil, but I tend to agree with the manual's schedule UNLESS the oil had been tested for moisture content before an extended change interval.

 

If new, change the fluids so you have a baseline. After that, follow the DIC.

 

Changing the fluid probably caused it; however, not the way you might think. You may have over-filled it and not realize it. According to the assembly/repair manuals from Helms, after filling the rear end up to the fill-hole, you're supposed to drive it for >20 minutes to get the oil up to operating temperature. Then, parked on a level surface, open the FILL plug, and allow the oil to drain to the level of the fill hole.

I made this mistake on my first differential oil change, and my symptoms were exactly as you described. Before you have the seal(s) changed, try this procedure. It worked for me.

To the original poster - I'd be more worried about brake fluid (brakes and clutch) than anything else. Brake fluid picks up water from the atmosphere, not only lowing the boiling point, but allowing the master and wheel cyllinders to rust. Look at the color of the brake and clutch fluid in the reservoirs. If they're clear, you're probably OK. If they're the color of Coca Cola, that's a bad sign and you may need to replace master, slave and wheel cyllinders - not cheap.

For synthetic motor oil, many manufacturers (Porsche, specifically) recomends a 12-month oil change interval. The main concern you'd have with a longer interval would be acidification of the oil, more likely due to short driving periods and the oil not getting hot enough than just low mileage. If, when it was driven, it wasn't just driven a mile to the grocery store and back, 2 years is probably OK. You can have the oil tested if it really concerns you.

For coolant, if the Dexcool is original, the corrosion-preventive additives are long-gone. You may have some internal corrosion that you can't see, but it's probably not too bad if the car doesn't over-heat. I'd get that changed as well - but not worry too much if the car stays relatively cool in high-load and low-speed conditions.

 

crap. I misread your post. It's pry not a sign of engine damage. Look at the DIC and see if it says its due. As for dexcool...just change it out.