Oil change by date, versus by mileage - how important?

Quickly darkening oil can indicate blow by.

A good friend years ago, who had a Mercedes diesel, said it would darken the oil within a few minutes after the change.

Thanks for the input. Twice a year sounds reasonable. Hm, Subarust is probably due, the MR2 I think we did early this year. ...crap it might be due as well then. Probably get them both early fall and maybe beginning of summer.

mtn wrote:

wbjones wrote:

mtn wrote: That 3 months 3000 miles came about... 60 years ago? Are you really telling me the oil hasn't improved since then, even dino oil? I go by mileage, unless we're talking about something like a Masarati.

I'm glad you're not the one taking care of my track car

Sorry, I should have been clearer: I'm talking about a DD.

I knew that … just pulling your leg ...

spitfirebill wrote: Quickly darkening oil can indicate blow by. A good friend years ago, who had a Mercedes diesel, said it would darken the oil within a few minutes after the change.

That's part of it I assume.

I feel like a lot of the 10k oil changes are great and all, but may not apply once rings/seals start to wear around 200k miles or 20 years old.

ProDarwin wrote:

wbjones wrote: dark usually just means it's doing it's job …or so I've always been told

Since we have oil experts in this thread... what makes it turn dark? I run synthetic in both cars and do 5k changes. Both are "sensitive" to gunked up timing chain tensioners, and my DD is also sensitive to gunked up oil rings. The Saturn will blacken oil with a quickness. Does that impact it much? If I could get them down to approx. once/year, that would be great.

Oil traps particles to keep them from creating wear. Oil that is clean and clear isn't trapping many particles. Particles can be anything from wear (iron, chrome, alum etc), to dirt or contaminants (water, fuel, coolant). Wear particles and dirt are easy to trap and keep suspended in the oil for a finite period of time. After time, the oil loses it's ability to to hold the particles in suspension and the start to drop out and create wear.

The only safe way I know of to extend intervals is long term sampling and high quality oil/filters.

So, what if your ancient 22re burns through a quart a drive and only smokes on start up? I haven't changed my filter in 7k, but my oil? Well that gets changed regularly... Usually with each fill up.

Even Amsoil recommends not over 1 year.

Ford, on my Fiesta says 10k or one year for normal driving. Heavy duty- 7.5k or one year.

Trackmouse wrote: So, what if your ancient 22re burns through a quart a drive and only smokes on start up? I haven't changed my filter in 7k, but my oil? Well that gets changed regularly... Usually with each fill up.

If you burn more than sump load in say 6000-7000 miles, just spin on a filter every 5000 or so and call it good.

My DD cars that get full synthetic get changed 2x a year. This works out to about 7k per change. Cars on syn blend are on the same schedule but they are driven much less. I have it planned so that they all get changed 2x a year that way.

ProDarwin wrote: I feel like a lot of the 10k oil changes are great and all, but may not apply once rings/seals start to wear around 200k miles or 20 years old.

With good oil you may never get much blow by. I ran full synthetic in my Malibu since new changing it every 15k miles and at 400,000 miles I was only losing about .5 qt every oil change mostly from the rear valve cover.

Both of my cars were designed for full synthetic and both of them get less than 3000 miles per year. So they get changed once per year.

wbjones wrote:

mtn wrote: That 3 months 3000 miles came about... 60 years ago? Are you really telling me the oil hasn't improved since then, even dino oil? I go by mileage, unless we're talking about something like a Masarati.

I'm glad you're not the one taking care of my track car

Why? Because you prefer habit/hearsay over data?

The BRZ track guys are obsessed with Blackstone oil analysis. Millers synthetic, for instance, has been shown to handle 3000 miles of TRACK only miles while running E85 and still be plenty good for more abuse, or 7500 hard street miles and Auto-X on E85 with plenty of life left.

And these are cars that run insane oil temps. Just driving around on the highway earlier doing mid-throttle pulls to let the ECU relearn the E85 tune saw oil temps in the 220-225 range (OBD-II signal) with it only 80 outside.

But to be fair, that is $225 a case oil (for 10 liters).

I have yet to retrofit a pcv system on my daily. It still has a draft tube.

I change the oil with napa branded dino stuff when the car starts smell bad at idle. Works out to be about every 4k.

Im interested in this subject. My miata likes to let the lifters (hla) tick when its due which is convenient usually around 3k. My girlfriends 08 accord burned all the oil in the sump before 3k with 5w-20 (it has a oil "life" sensor thingy) but now we switched to 5w30 its now at 3500 and indicated 50% life left and the oil still looks okay. Not burning anything now...funny how a newish car works with only 80k miles burns more oil than our 250,000mile 27 year old redblock

z31maniac wrote:

wbjones wrote:

mtn wrote: That 3 months 3000 miles came about... 60 years ago? Are you really telling me the oil hasn't improved since then, even dino oil? I go by mileage, unless we're talking about something like a Masarati.

I'm glad you're not the one taking care of my track car

Why? Because you prefer habit/hearsay over data? The BRZ track guys are obsessed with Blackstone oil analysis. Millers synthetic, for instance, has been shown to handle 3000 miles of TRACK only miles while running E85 and still be plenty good for more abuse, or 7500 hard street miles and Auto-X on E85 with plenty of life left. And these are cars that run insane oil temps. Just driving around on the highway earlier doing mid-throttle pulls to let the ECU relearn the E85 tune saw oil temps in the 220-225 range (OBD-II signal) with it only 80 outside. But to be fair, that is $225 a case oil (for 10 liters).

(edit: forgot to put this in here, with an oil cooler, I'm running 225° on these hot summer sessions … (mechanical oil temp, and pressure gauge)

FWIW those are new, modern engines … mine was designed more than 25 yrs ago and I have run into an oil related problem (in my opinion because I tried to get ONE more track weekend out of an oil change)

I was also running Amsoil signature series oil … but that's more of a street oriented synthetic oil … now, until I run out it's Amsoil dominator series … more of a track oriented synthetic oil … when it's gone I'll switch to Mobile 1 … available ANYWHERE … as are good quality oil filters

and after talking to Ron with Discover Parts, and finding out what the Porsche race team, headquartered at AMP (where his business is) run (off the shelf Mobile 1) … I'm pretty sure I'll be ok

I don't change by date. Ever.

I drive a lot on my DD, and can feel and hear the difference if the oil gets near 5K. But it's a PSD- they really like clean oil.

I change it every 3-4K, and use synthetic. It keeps it very happy. Yeah, I may spend a little more on oil than recommended, but I've gotten 480K out of it, so it's pretty hard to argue with.

My wife's car, usually 4-5K on synthetic.

Beaters don't get oil changes.

Race cars get much more frequent.

z31maniac wrote:

wbjones wrote:

mtn wrote: That 3 months 3000 miles came about... 60 years ago? Are you really telling me the oil hasn't improved since then, even dino oil? I go by mileage, unless we're talking about something like a Masarati.

I'm glad you're not the one taking care of my track car

Why? Because you prefer habit/hearsay over data? The BRZ track guys are obsessed with Blackstone oil analysis. Millers synthetic, for instance, has been shown to handle 3000 miles of TRACK only miles while running E85 and still be plenty good for more abuse, or 7500 hard street miles and Auto-X on E85 with plenty of life left. And these are cars that run insane oil temps. Just driving around on the highway earlier doing mid-throttle pulls to let the ECU relearn the E85 tune saw oil temps in the 220-225 range (OBD-II signal) with it only 80 outside. But to be fair, that is $225 a case oil (for 10 liters).

oh … and one more thought on the subject of race cars and frequency of oil changes … there are well know race teams out there that change the oil after every weekend … and some even after each session (think drag race teams) …

so … lots of leeway about how often … pretty much do what ever makes you feel the safest

go on one oil change for the entire season … whatever … change every session … again whatever

Really? Every drag pass? That's gotta be high dollar oil tycoon budget...

In reply to Trackmouse:

The serious top fuel drag racers REBUILD THEIR ENGINES after EVERY PASS (and have 75 minutes to do it).

SVreX beat me to it … don't know about Top Alcohol … but Top Fuel, and Funny Car both do complete tear downs between runs … so for sure not re-using the oil

I ran Amsoil Signature series 5W/30 in my ZX2SR for as long as I owned it. 10yrs an 75K miles. DD, many track days, ice racing. Just followed my once a year changes.

There is a lot of good stuff here, but some misinformation too.

The color and clarity of the oil is a very poor indicator of its condition. Oil has four main properties; pH buffers, viscosity additives, solubility, and wear additives. Any one of those properties can degrade with time or use. Visual appearance is not an indicator of any of them.

If you drive a lot, your limiting factor will be mileage. The oil will likely reach its limit on wear, viscosity, or solubility long before its pH is out of whack. If you have an engine that sits for long periods, chances are you'll have pH and wear (since some wear additives are volatile and evaporate) issues before anything else.

But guessing is just that; guessing. The only way to know is either change the oil more frequently to make sure you don't reach those limits, or test it.

chiodos wrote: Im interested in this subject. My miata likes to let the lifters (hla) tick when its due which is convenient usually around 3k. My girlfriends 08 accord burned all the oil in the sump before 3k with 5w-20 (it has a oil "life" sensor thingy) but now we switched to 5w30 its now at 3500 and indicated 50% life left and the oil still looks okay. Not burning anything now...funny how a newish car works with only 80k miles burns more oil than our 250,000mile 27 year old redblock

My buddy got a new 08 Accord and so did his sister as Xmas gifts. Those cars burn oil like it's their job.

This makes me want to get an oil analysis done on the DD. I'd be hesitant to spend $20 for one, but if it tells me I can get oil changes down to once/year I'm all for it.

wbjones wrote:

z31maniac wrote:

wbjones wrote:

mtn wrote: That 3 months 3000 miles came about... 60 years ago? Are you really telling me the oil hasn't improved since then, even dino oil? I go by mileage, unless we're talking about something like a Masarati.

I'm glad you're not the one taking care of my track car

Why? Because you prefer habit/hearsay over data? The BRZ track guys are obsessed with Blackstone oil analysis. Millers synthetic, for instance, has been shown to handle 3000 miles of TRACK only miles while running E85 and still be plenty good for more abuse, or 7500 hard street miles and Auto-X on E85 with plenty of life left. And these are cars that run insane oil temps. Just driving around on the highway earlier doing mid-throttle pulls to let the ECU relearn the E85 tune saw oil temps in the 220-225 range (OBD-II signal) with it only 80 outside. But to be fair, that is $225 a case oil (for 10 liters).

oh … and one more thought on the subject of race cars and frequency of oil changes … there are well know race teams out there that change the oil after every weekend … and some even after each session (think drag race teams) … so … lots of leeway about how often … pretty much do what ever makes you feel the safest go on one oil change for the entire season … whatever … change every session … again whatever

True, I could change the oil every day after going to work and back.

But data > hunches.