How long to keep oil in engine

[StadEMS3]

I always see mileage oil change intervals but what about time? My car rarely gets 1k miles per year on it, and sits in the garage most of the time. I changed the break-in oil after I put in the 331 stroker and then put in Royal Purple, that was 3 years ago. The oil still looks fairly new....

I know...drive it more....

 

[Chythar]

IMHO, oil does not break down or get dirty just by sitting. The whole "3 months or 3000 miles" is more useful for those people stuck in rush hour traffic, idling but not moving. Or if all you do is short trips to the store. Too bad we don't have an RPM counter as well as an odometer - we could simply say 1.5 million engine rotations between oil changes. Or a sensor in the oil filter telling you when the oil filter is plugged and the bypass is being used.

I don't put a lot of miles on my GT, nor do I sit idling in rush hour traffic. So I go simply by the 3000 miles. Seems to be good so far.

 

[HISSIN50]

I'd worry about qualities in the oil becoming acidic after some time. I would use a synthetic and change it once a year.

 

[Labora]

I'd change it at least every year. But that is just a gut feeling..

 

[94-302-vert]

I'm with these guys. Oil will get acidic just sitting.... so run synthetic and change it yearly OR run conventional and change it 2x a year....

Better safe than sorry. The last thing you want is to have to rebearing that engine due to saving on oil changes....

 

[Chythar]

Never heard about oil going acidic, something to file away in the mess I call a brain. Personally, I average around 7K a year these days and I use Mobil 1 synthetic every 3K miles or so. Double coverage by the sound of it.

 

[revhead347]

Royal Purple is a synthetic, and won't break down or get acidic. Only conventional oild does that. After 3 years it's probably a good idea to change it though.

Kurt

 

[HISSIN50]

The acidity is a byproduct of condensation. How does RP not allow this to occur?

 

[madams74]

Condensation can only occur if warm up / cool down cycles are short. I have always seen the worst thing for an engine is to start it up and only run it for short burts at a time. An engine that only goes a few miles up the road and back to the store a few times a month is in worse shape than one that obtains enough temp to prevent condensation. I had a 400 CI Ford engine in a truck that had a valley pan in between the heads under the intake once. The valley pan had rust underneath it right in the middle. It was the condensation that collected on it and rusted the middle of it out. Royal Purple is synthetic and the materials are not petroleum based. I would think it could sit 3 years easily. If you only drive it 1000 miles a year then why dont you just save yourself a buck and buy regular oil. You wont hurt anything.

 

[HISSIN50]

Getting an engine up to operational temperature only has to do with flashing moisture, not whether it has previously formed or will form again (it will).

Condensation occurs with environmental differentials.

 

[wytstang]

I asked this very question to Black Stone Labs, they responded with basically not to worry about oil sitting for long periods of time while in the motor. It takes me 11 months to reach 5000 miles (at least). So since they do my oil testing I asked them about the length of time it takes could the oil start to lose viscosity or just break down in general. They basically said no. So I stopped worrying about it. I run MC 10w30 which is a synthetic blend. Would like to add due to a leaky rear main seal I do have to add a quart in between oil changes.

 

[Grn92LX]

Change it once a year at the beginning of each cruising season.