[GordonGeesey]

I'm running a modern, high-zinc fully synthetic oil in my '65. I'm just curious as to everyone's thoughts on this:

I put less than 1000 miles a year on my car. It's strictly a fair-weather cruiser and is not raced or abused. The car is stored in a climate-controlled garage. Can I safely extend my oil change intervals to 2 years? I guess what I'm really asking is this - does synthetic oil "break down" over time like conventional oils do? Aside from getting dirty (which mine doesn't appear to be), is 2 year old synthetic oil still performing as designed?

[geeteeohguy]

Originally Posted by GordonGeesey

I'm running a modern, high-zinc fully synthetic oil in my '65. I'm just curious as to everyone's thoughts on this:

I put less than 1000 miles a year on my car. It's strictly a fair-weather cruiser and is not raced or abused. The car is stored in a climate-controlled garage. Can I safely extend my oil change intervals to 2 years? I guess what I'm really asking is this - does synthetic oil "break down" over time like conventional oils do? Aside from getting dirty (which mine doesn't appear to be), is 2 year old synthetic oil still performing as designed?

I have a fleet of old cars, have been using diesel spec oil in them all for the past 23 years, and change the oil at 3000 mile intervals. That usually takes two years, but on a couple cars, it can take 4 or more. I've never had an issue, and have done teardowns and reseals, and the engines and bearings look excellent. Currently have 90,000 miles on the rebuild I did on my '67 37 years ago, and when I resealed it in 2011, it still looked new inside (80+k miles at that time). Disclaimer: I don't over-rev or race my old cars. Diesel spec oil is not intended for high RPM use due to anti-foam qualities.