How do you really know your synthetic is really living up to its claims? I have 100k on a 93 Z71 with a 350 and been on Penzoil 15-40 all its life. It does not use oil and still passes emissions test with flying colors. I fully expect 200k out of it. The reason I ask this question is because I used to mechanic for a company where we ran a fleet of trucks, both gas and diesel. We did lube oil anaylsis every 90 days on everything except our few pick ups. We tried synthetics (Mobil) for about 18 months in a test group and weren't pleased. Chrome and iron content was almost always high ,sometimes at critical levels, indicating high ring and cylinder wear. The trucks were serviced on the same intervals as the rest of our fleet, on regular oil, which rarely would come back with a bad report. We finally switched away from synthetics all to gather. We couldn't justify the additional expenses. I firmly believe in oil anaylsis as a maintenance tool, but it , like oil changes, has to be preformed on a regular interval to be of any value. I have been made aware of air filtration and coolant leaks months before I would have known a problem existed by trace amount of contaminates in the oil, made evident by anaylsis.
Just my $.02 worth, thanks.
Don
[This message was edited by Hummie2 on November 25, 2002 at 07:01 AM.]
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