Originally Posted By: MSTUEBER
I have a 1992 Miata that I only put about 400 miles a year on it. I changed the oil last month. Do I need
to change the next year or will the oil be good for a few years. I only drive it on nice days and sits in the garage.
Oil has no idea how old it is. As long as conditions are good, and the add-pack isn't overwhelmed, oil can last a LONG time.
There are some UOAs here (admittedly not the norm) that show 3-5 years is easily doable, presuming the engine systems (air filtration, coolant, PCV, etc) are in good shape. I run 3-4 years in a few of my low-use equipment applications and have never had a bad UOA. There is a UOA here somewhere from a 11 year (ELEVEN!) OCI. Low use and long storage. And yet the UOA was fine; both engine and lube were not compromised.
You can rest assured the oil will EASILY go 3 years, given your 400mi/yr average. And no, you don't need a syn to do this, either. There's no evidence that shows a syn is any better at long term storage than a dino, despite all the marketing hype and BITOG rhetoric you'll hear.
You didn't ask, but the corresponding topic is that of the filter. A "normal" cellulose filter can easily go 3 years at your use level as well. 5 years is a bit "iffy" according to Jim Allen, who got the insider tour at Fram a few years back. A fully syn media filter could probably double that easily; 6-10 years is conceivable.