So there are a few ways to determine that your oil is getting old and is not doing its job anymore. Some of those methods have been debated but they all get the job done.
1) Send a sample of oil to the lab get results back that are concidered very accurate, this wil normally cost you less than 25 buck
2) Or look at the dipstick and try and tell what is the oil looking like from there, many folks argue this process because it is not going through an actual lab and being scientifically analyzed. But listen up this may be able to be usefull.


FOR THOSE THAT DONT WANT TO SEND AN OIL SAMPLES AND LIKE TO LOOK AT THE DIPSTICK AND DETERMINE IN WHAT SHAPE THE OIL IS IN:

Oil is not like a fine wine that gets better over time. Instead, it ages at a rate that is influenced by driving conditions, fuel quality, engine age, motor oil quality and climate. If not changed in time, your oil will break down and fail to protect your engine.
So, let’s take a close look at the oil on the dipstick. The oil should look smooth and glossy and somewhat transparent. If it has sludgy deposits or grainy particles of dirt, it’s time for an oil change. The same is true if the oil looks too thick, is too dark (opaque), and/or has a putrid rotten-cheese smell.
If you still don’t know whether you need an oil change, consider doing a blotter spot test.
Oxidized and contaminated oil will lose interfacial tension. A simple test for interfacial tension is to place a drop of used oil from the dipstick on the surface of water. If the oil drop spreads out over the water’s surface (instead of beading up like a new oil) it may be time for an oil change.

 

Thank you for the good tips on checking for bad oil, sir .

 

Can't we just change it at the recommended 3,750-mile intervals as recommended by the manufacturer and call it a day?

 

Remember the recommended cycle is for normal use. Be thoughtful of what conditions you're putting your motor through, and analyze it that way. One of the things testing does well is it tell you the sheering of the oil, and if you should be changing sooner or later. Extended abuse of the engine, say drag, autox, or track, will reduce the oil life. Therefore, mileage is not a clear indicator.

 

Not exactly... 5,000 miles is the recommended cycle for "normal" use while 3,750 miles is the recommended cycle for "severe" use.

 

Not so simple as that because I would not want to wait to change my oil after say, 3,750 ROAD COURSE driven miles.

 

I don't know if you'll have 3,750 road course driven miles, unless you have a dedicated track car... in which it would be a no-brainer to change your oil far more frequently.

 

If you have that many miles on a track you rock. I've been told that oil should always look darker than lighter because it means it's working and cleaning out your moving parts. Makes sense to me not sure if it's true.

 

very thorough

 

I have put over 175 miles on one track event (this is usually done during open track/test and tune days). Sometimes it can get even higher if the evo is being shared by another driver that day. That gets really hard on the car though, so I dont like doing that too often. 3750 miles is about 2 seasons of regular track outings, or about 25 track events give or take. Thats some super oil if it could last that long,haha.

This is all on a dedicated track car that doesnt get driven on the street regularly btw.

 

That makes perfect sense then. I was referring more to daily driven Evos rather than dedicated track cars, since the thread didn't seem to be about one particular kind of Evo, but thanks for clarifying.

 

I wasn't attempting to debate normal vs. severe duty, and when oil should be changed. It wasn't my point, but i think others covered in their posts. Its all subjective on what is safe, and in my opinion, you can't put a mileage on that. My example would be the stress my car sees with a co-driver at the track. On many occasions, my car see up for 50 mins of straight track time because we run back to back. This puts a lot of stress on the engine, and oil, and so I change it as I feel is needed. For me, the 3,750 miles for severe duty based on the factory manual is not acceptable.

 

What if the car is in storage or only driven once in a while? How often should the oil be changed in this case?

A lot of guys I know are wondering the correct answer to this.

 

I've always heard 6 months regardless of mileage. I've never had my car sit for more than 1 day though, so I can't offer personal experience.

 

I asked Blackstone Lab about this since I change oil every 10-12 months/2K miles. They said oil doesn't expire with age. With use though, oil will become abrasive from contamination/metal so they often look at mileage that an oil has acquired rather than calendar months to suggest oil change intervals.