- Mar 21, 2005
- Elderly County, Florida
Hi fellows - me again. Yesterday, I changed the oil in my sister's truck. 2003 Chevy Silverado half ton, 5.3 V-8, (Mobile 1 10W30). While pouring in the last quart, I asked her if she had ever flushed her cooling system. She said she didn't know they needed flushing. The radiator on this truck does not have a cap on the rad, but instead has an overflow tank where you add fluid. I took the cap off that and looked inside. The sides of this tank is covered with these little bumps, (like pimples). The coolant itself is very dark and looks like syrup. It's the original factory fill, (this truck belonged to my Dad and he gave it to my sister - so I know if she never changed it, it's never been changed as my Dad never changed it). The truck has 167,000 miles on it. Additionally, I took a white paper towel shop rag and wiped the inside of the oil cap and inside the filler tube on the engine, the residue on the white paper towel was a dark red/brown-red color. She got the truck with 120,000 miles on it and has always used Mobile 1 10W30 with every change, changing oil every 6,000 miles, (I changed it for her yesterday as money is tight for her and she was worried because she was at 6,800 miles on current change). When my Dad bought the truck new in '03, part of the deal was a free lifetime oil change every 3,000 miles which he faithfully did. I'm sure they used a conventional motor oil, but oil and filter was changed every 3,000 like clockwork from 0 miles to 120,000 miles. Since 120,000 miles, she has changed the oil every 6,000 miles with Mobile 1 like clockwork. So okay, here are my questions: 1. The dex cool is obviously bad - past time on both miles and age. It appears to be turning into the famous dex cool sludge. Currently, she has no cooling issues. Should I flush or should I leave well enough alone? I fear if I get to cleaning, it might break something loose inside and then she'll have cooling problems. I was tempted to try the TSP cleaning yesterday but was fearful this might clog the system AND I'm only in her neck of the woods once a week and she would have to drive the truck a full week with the TSP in her cooling system. Is that too long to do this? 2. What is this redish/brown red coating inside her motor? Is that from the dexcool? Is this an indication coolant is starting to leak into her motor? Is this the beginning of a head gasket issue? This vehicle is her only ride and she doesn't have the money for a trade. I'm fearful of doing something that will really mess up her truck. On the one hand, I want to help her maintain her truck but on the other, I don't want ot leave her stranded with some bone head move on my part. What say you guys? Any advice and guidance will be most helpful and welcomed. Thanks - Glenn.