Learn me: Oil Change Frequency

"Changing oil is like changing underpants - there is nothing to be gained by extending the service interval."

Contrariwise, I tend to drive some of my pleasure vehicles rather infrequently -- think 1k to 3k/year. 

Blackstone has confirmed that, even after two years on an oil change, that the oil is still in excellent shape. I tend to run Mobil 1 EP, which is largely a Group IV oil if memory serves. 

Changing the oil more frequently certainly doesn't hurt the car, but it is wasteful of resources and money. 

In reply to brandonsmash :

Blackstone has determined the oil doesn't have contamination after that long. They're not actually checking oil properties for signs of the oil itself holding up. That's my main concern with their test suite and why I offer what I do. 

A lot of M1 was group IV, but since the description of synthetic changed they have migrated many of their synthetc fluids to group III+, and there is nothing wrong with that. Group III+ is still highly refined and will still meet or exceed the needs of the OEM with the right additives. 

By what method would the oil break down, then? It's not like back in the 1990s where we were often using oil that was barely shelf-stable. I figure if my oil doesn't show excessive contamination or signs of use, then a good synthetic oil won't just break down from sitting inside a sump. 

Obviously extended service intervals change with use: If I've just driven on the street, no big deal. If I've done track events or the like, that precludes extending the oil service life. 

I just drained an engine that should have 5qt in it, had about 7. The other two are likely methanol and water, so that's one way 

brandonsmash said:

By what method would the oil break down, then? It's not like back in the 1990s where we were often using oil that was barely shelf-stable. I figure if my oil doesn't show excessive contamination or signs of use, then a good synthetic oil won't just break down from sitting inside a sump. 

Obviously extended service intervals change with use: If I've just driven on the street, no big deal. If I've done track events or the like, that precludes extending the oil service life. 

 

Sitting? No, you can still see additive drop out with some of the heavier elements they use (Boron is one) but it's not that critical. Usage is where you will see oil breakdown. Oil temps too high for the oil in use? Too much pressure (think old pushrod engines with flat lifters)? Those can all accelerate oil decay and deplete it's ability to protect faster than anticipated. 

I'm not sure how you determine "signs of use". Color of the oil is a horrible indicator unless you're referring to a hydraulic system that should not see wear, or turbines but that's not what we are talking about here. 

Track driving doesn't preclude oil service life if you're doing or done testing. The Rio is my outlier, but the rest of the vehicles that have seen track time have not had any significant percentage decrease in oil longevity IF you're using the correct oil for your application. 

I'm not trying to sell you anything. I've said before that testing isn't necessarily a smart financial option for most people. But if you want to know the actual answer to the question that is being asked and not a bunch of peoples random opinions, testing or engine failure are pretty much your only two options. One can be more costly but entertaining to watch. One is pretty boring and cheap.

In reply to Paul_VR6 (Forum Supporter) :

meth injection gone wrong?

In reply to bobzilla :

I suppose maybe there are some things I don't know, then, about evaluating oil. When BSL gets to me and says that the oil looks fine, I tend to trust them. It seems wasteful to change oil every year when the vehicle has seen 2k (or fewer) miles on street. Mobil 1 EP calls for a service life of 15k, so a bit over a year of "average" driving in the US.

I have opinions on their reports but I'll keep it to myself. There's a reason I felt there was an open spot for good analysis for amateur racers and am trying to do what I do. 

Yes, changing oil that is still serviceable is extremely wasteful both from an economical and an environmental standpoint. That's why you test. 

I've done a lot of used oil analysis and 5k for a street car with any quality synthetic is good regardless of time. Any modern car has a sealed PCV system so I dont think time affects the oil as long as the vehicle is driven at some point. I have a Toyota Land Cruiser that gets driven maybe 1k a year and so it goes years between oil changes and engine is clean, no sludge and analysis looks perfect. 

On my track car I'm still trying to figure it out. I had settled on 3 hpde weekends but after my rebuild I've been changing and checking UOA each weekend and its been showing some wear. At this point not sure if it matters tho and just might go back to 3 weekends (assuming 2 full days each)

In reply to StuntmanMike :

Send me your reports with the car info. You may just need to use a different oil for this engine. It happens.