I thought this was interesting. I tend to go by mileage more than time, but I know many who do the twice a year change as well. From MSN: When it comes to caring for cars we cherish, it's better to play it safe than sorry. If you're like me, you've been changing your oil every six months whether you've done 900 miles or 5,000, wondering if you were premature when it doesn't come out inky black. Well, those days are over for me, because oil analysts at Blackstone Laboratories have tested old oil from a variety of sources, and they say it's the miles that matter most. Host Joe Adams recounts pulling a half-full bottle of Mobil 1 0W40 off the shelf, and contacting its producer to find out more about it. The bottle turned out to be almost 14 years old, and Mobil 1 said its age meant it'd broken down and wouldn't properly protect an engine. But when pressed, it wouldn't explain how, so Blackstone ran it through a battery of tests. Blackstone said it tested a variety of the oil's characteristics, from measuring additives to water content, flash point, viscosity, insolubles present, and the oil's ability to neutralize potentially harmful acids and bases. Even though the oil was made in September 2010 and had been sitting half-full for an unknown period, it tested just fine. That led to several follow-up tests of other old oils from varying sources to work out the circumstances that cause oil breakdown—and the answer was pretty clear. "Calendar time is no reason to rule it out," Adams said of old oil. "Miles are what you need to be keeping track of." Full story: https://www.msn.com/en-us/autos/aut...n&cvid=c51044b57f214d90b669dfad6b7e1131&ei=55
Interesting. I'd think that old oil stored in a sealed container might be fine, but sitting in a crankcase and exposed to a normal, humid atmosphere might be a different matter. Devon
If your 430/455 is stock and you do not race the car you are. Keep the oil level up to spec and drive the car always to operating temp there is no problem at all. I've done this for years. Did an oil change in 2009 and than again in 2020. Did approx. 4000-5000 miles. Nothing wrong with the mineral oil that came out of the engine. But ofcourse the mineral engine oil here is a lot better
I see stuff at bottom of white Castrol containers after pouring on fresh off the shelf oil. I figured minor rust in containers it's made in. Many other brands are not white so you don't see it.....I'm not throwing away my old sealed oil. I recently started up a 70 455 that had sat for 30yrs with Kendall GT-1 in it....seems fine. I did change it after running for 30 min.
My cars, even my daily drivers, sit in heated and air-conditioned garages. I don't cool or heat to human comfortable temps, but I keep the humidity down and the temps are moderated. I heat to 50°F and cool to 80°F. I have never changed my oil by age and I suppose this justifies my multi-year oil change routine. I've always thought oil that isn't abused isn't used up. I believe in break-in oil and a quick first change but after that, let it be until the miles are hit. I last changed the oil in my 455 car in Feb of 2022. Before that was Oct 2016. It was 2000 miles between changes, and I only did it then because I went racing the previous week in 2022. My daily driver has a factory recommended 10,000-mile change interval. I did it every 5,000 miles but it was still over a year between changes some years due to COVID and retirement.
