Learn me: Oil Change Frequency

I've tried several searches, but have come up empty.

I've recently completed an engine swap (JDM WRX into 98 Legacy Wagon), and am determined to keep on top of maintenance. My problem is that I'm not driving much at all (and when I do, boost presents itself with great enthusiasm). Five months in, I've yet to have driven 3000 miles, and that includes a 900+ mile drive across country.

I fret, especially since I now live in a Subaru desert (W. Monroe, LA) and the engine is putting out a little more than factory hp (233 whp [~310 hp at the crank?])

The old trope says 3k miles or 3 mos, whichever comes first.  If my car is only seeing maybe 6k miles/yr, and perhaps a couple autocrosses too, when should I be changing the oil? 

TIA!

This thread will be interesting.

As for me, I change more frequently than what the normal internet consensus says that is necessary. 

Crash Enburn said:

The old trope says 3k miles or 3 mos, whichever comes first.  If my car is only seeing maybe 6k miles/yr, and perhaps a couple autocrosses too, when should I be changing the oil? 

That trope was created by Quickie Lube places to try and sell you more oil. Generally, I look at the factory interval and subtract from there based on if the engine is modified, what kind of use it sees (stress like racing, towing, etc), the environment (if it's very dusty, etc), and whether it's synthetic or organic oil. 

Having said all that, for our daily drivers, I just do it every 5k because it's easy to keep track of. The turbo vehicles get full synthetic, the NA ones get regular.

I get an oil change when I get inspected every year, but I average 4,000 miles a year.

Just check it every few months to make sure it's still there.

RevRico said:

I get an oil change when I get inspected every year, but I average 4,000 miles a year.

Just check it every few months to make sure it's still there.

I change the oil once a year in my cars that don't see a lot of miles.   mobil 1 synthetic and check regularly.

I've heard it said that changing the oil at least twice a year is a good idea since it gives you a chance to take a look at the underside of the car on a somewhat regular basis.

I drive 25-30,000 a year - I go 5,000 and at this mileage there is no burning over the 5,000 miles.  

Overkill?  1,000 guys will argue it is. 

In reply to Tom_Spangler (Forum Supporter) :

that trope has been around far longer than the Quickie Lube places.  i'm pretty sure 3 months / 3000 miles is called out in the owners manual for my old 66 Caprice.

I typically do every 5k, or once a year if I don't hit the 5k in that time period.

FWIW i go 5k on everything except the Odyssey. Ody gets 7500 (+0 -1125) because the reminder comes up at 15% and AK2 is a friggin' hawk on that reminder.  i try to push it to the full 7500 but she's on me daily when it gets under 10%.

i don't care if it's throwing money away.

I won't let the Bluetec in the Mercedes go over 5k miles.  The factory specifies a 10k OCI, but as much fun as it was to rebuild the motor and everything, maybe I don't want to do that again.  The Neon gets a change once or twice a year, depending on how many races it does.  The Miata hasn't had a change in a couple years since it's been parked in the shop while I futz around with the stupid rust repair.  I hit the Saab every 3k miles, which is probably too frequent, especially when you consider that it leaks so much oil it never really gets a chance to age that much...  The Mazda 5 gets a change every 5k, and the motorhome gets it every 5k miles or right before the trip to Daytona for the Rolex. 

maybe worth it to do an oil analysis? They'll check how much of the additive package is remaining and let you know if you can push the interval further. As a bonus you'll get the wear metal analysis so you can tell if something is about to blow up

Annually or 5k miles for most machines. It's easy to keep up with. Change it when the odometer rolls over a 5k or 0k number, or whenever the new registration comes in. Sometimes I get bored and change it anyway. 

Per Cummins, the RV is annually or 20k miles but it holds 7.3 gallons of oil.

Testing. That's how you figure it out correctly. You will need to make sure the lab is testing the oil properties and not just looking at contamination. I know a guy that does it if you're interested. Even has a thread on here answering questions etc. 

The longer answer that is guessing:

There are a lot of things that go into this. Capacity, useage, oil being used, engine condition, atmospheric conditions, tune, driving conditions, driving styles etc. As long as the engine isn't pulling a honda L15 and dumping copious amounts of fuel to the crankcase, you're using a modern correctly rated oil and not overheating the oil a rough first sample at 3k would be a good start. You test, and as long as the results come back positive add more time and test again. Do this until you reach that point where it's almost too long and back off a hair. For different cars of ours that could be 9k miles or 3k miles. The Rio holds just over 3 qts, gets the snot beat out of it and 3k is about as far as I am comfortable stretching it. The Sierra holds almost 7 and 9k isn't even a stretch.

In reply to gixxeropa :

Its not the ad-pack that is usually the problem. Oil wears out with usage. There is a finite limit to it. The 3 key indicators for oil life are viscosity, base number and oxidation/nitration results. 

In reply to bobzilla :

I shot you a PM. 

Fun note: the oil change indicator on the E39 BMW is based on fuel usage. It's assumed that if you are using more fuel, you are driving harder so you'll need more frequent changes. Which is a pretty clever way to do it.

Generally speaking, I don't change it anywhere near as often as I should, and usually use the color on the dipstick as an indicator.

I've already changed the oil (fret, worry, fret), and can no longer collect a sample. 

I'll probably adopt a 3333mi/6mo schedule. It's very likely overkill, but it should be cheap insurance. I'll collect a sample the next go-round and see what the results are.

Thanks, all.

In reply to Keith Tanner :

I can't say this enough, color of the oil is a terrible indicator and why you'll never see "color" as a test in any used oil analysis for engines. With that said if your gas engine has turned the oil coal black in a week, that could be an issue. 

bobzilla said:

In reply to Keith Tanner :

I can't say this enough, color of the oil is a terrible indicator and why you'll never see "color" as a test in any used oil analysis for engines. With that said if your gas engine has turned the oil coal black in a week, that could be an issue. 

Wife's former ALH 1.9 TDI turned new oil black before you got out of the driveway following an oil change. So, definitely couldn't use color to decide on that one.

I do it every 5K.  Its easy to see when its time so its less brain power.

This thread has made me realize I have not changed the oil since I bought my truck. Three years ago.  It still hasn't hit 3k miles.

Depends on the vehicle. Couple of my newer vehicles (2006-2011) tell me when to change it (6k miles or so). My 1997 Accord has a primitive oil change indicator that I use as a reminder (5k i think). The rest of the cars every year or so since they don't get driven often (500-2,000 miles per year).

turbo subaru's are known to be tough on oil, and moreso when you've upped the boost.  I'd start out at 3500 miles or 1 year of use, and do an analysis, looking for viscosity breakdown, trace fuel in the oil, and focusing mainly on the following wear metals; Potassium (indicates coolant in the oil aka dreaded headgasket seepage), Chromium (ring packs and early threat warning of ringland damage), Lead and/or silver (rod bearings, i think the GR series imprezas had some silver in the bearings), and any high (20+ ppm) levels of Aluminum which are your block and piston wear indicators.  

almost every subaru EJ used oil analysis i've seen over the years that showed high numbers in those categories ended up with that respective issue.  they like to run the oil hot and those thin rod bearing cross sections put a lot of pressure on the oil too.  i probably wouldn't cross over 5k miles of use no matter what.

ScottyB said:

turbo subaru's are known to be tough on oil, and moreso when you've upped the boost.  I'd start out at 3500 miles or 1 year of use, and do an analysis, looking for viscosity breakdown, trace fuel in the oil, and focusing mainly on the following wear metals; Potassium (indicates coolant in the oil aka dreaded headgasket seepage), Chromium (ring packs and early threat warning of ringland damage), Lead and/or silver (rod bearings, i think the GR series imprezas had some silver in the bearings), and any high (20+ ppm) levels of Aluminum which are your block and piston wear indicators.  

^^ This.  Subaru changed what they had published in their owner's manual and dropped the factory suggested interval to 3500 miles. I'd start there and either keep doing it on that schedule or do analysis to see how far you can go.