Do you trust oil life monitors in newer cars?

[JCH13]

More precision and performance should mean more frequent oil changes, not less.

I don't believe them because they have a vested interest in reducing their "free maintenance" costs, and zero interest in your car lasting past the warranty term.

BMW enthusiasts and mechanics say the 15000mi interval is too long.

You have a good point with their vested interest, but your first statement is a non sequitur. For example, a tight fit between the piston rings and cylinder walls will result in burning less oil and less blow-by entering the oil sump, both of which prolong oil life.

 

[Throckmorton]

You have a good point with their vested interest, but your first statement is a non sequitur. For example, a tight fit between the piston rings and cylinder walls will result in burning less oil and less blow-by entering the oil sump, both of which prolong oil life.

But aren't the surfaces also more sensitive to proper lubrication when tolerances are lower?

 

[Rifter]

Every 3 months is crazy, unless you are using the engine very hard.

My cars i autocross and my truck i offroad so they see hard use. And the cars will usually hit 5000 miles before 3 months anyways.

 

[Eli]

More precision and performance should mean more frequent oil changes, not less.

I don't believe them because they have a vested interest in reducing their "free maintenance" costs, and zero interest in your car lasting past the warranty term.

BMW enthusiasts and mechanics say the 15000mi interval is too long.

No.

Oil contamination is what ultimately destroys your oil and makes you need to change it. If the engine's tolerances are tight, the oil will stay cleaner longer because combustion byproducts are not entering the oil.

But aren't the surfaces also more sensitive to proper lubrication when tolerances are lower?

Yes and no. Oil can do a better job in an engine with tight tolerances because it isn't being pounded out and sheared by sloppy fitting parts.

Oil is oil right up until your TAN goes high or TBN goes too low. As long as it's maintaining proper viscosity, you're good to go. That's why oil analysis is critical if you want to push the envelope at all. A high TAN is far worse for your engine than say, redlining it. The acids literally eat away the metal inside your engine, accelerating wear far beyond what you would see in normal use.

That's the danger with leaving your oil in the crankcase for a year. That implies not driving very much, which is much, much worse for your oil than regularly driving it, which heats it up and burns contamination off.

 

[dbk]

I go by what my Fit says.. usually down to 15 or 10% and it avgs out to be at like 6000~6500 miles...

 

[CraigRT]

I changed my factory fill early, but other than that, plan on following OLM.

 

[hanoverphist]

It's like your gas gauge, the first hundred miles, the meter will not drop as dramatically as the remaining amount later down the road.

My 06 Civic is the same way but in the end, it always being 7500 miles when the meter say i have 15% oil life left.

my 98 civic manual and maint schedule says 7500 mi for oil change also. i was surprised at such a large interval, but they know their engines way better than i do

 

[Eli]

The engine isn't really the variable, the driving conditions and to somewhat of a lesser extent the oil itself are.

Regarding the 7500 mile oil change, there's more to the story than that. They don't just universally call for a 7500 mile oil change, there are tiers depending on the severity of use.

It's usually 3750 for Severe duty, 5000 for Normal Duty and 7500 for Light Duty.

The problem is that most people don't understand the definition of those terms, and would consider a quick, short trip to the store "Light Duty" when in fact that's about as severe as it gets, as far as your oil is concerned.

Regardless, I would never assume that the manufacturer of something knows best. In the case of something like an engine that has so many variables thrown at it they're hard to count, the only way to know how long your oil will last in your specific engine under your specific driving conditions and habits is to have it analyzed.

Otherwise, you must (hopefully) change it at a conservative interval.

 

[the DRIZZLE]

I don't have one but I would be pretty skeptical. Don't some BMW's have intervals of like 15k? That's asking for trouble IMO.

 

[alphatarget1]

Subaru says 7.5k for oil changes in the new WRX/Sti and Forester (all come with synthetic from the factory). I would not wait 7.5k for an oil change in a turbo-equipped vehicle, period. I will do ~5k on high-quality synthetic, which for me will be a little less than 2x a year.

That depends on how you drive your car doesn't it? If you barely ever boost, I think long oil changes are probably OK.

I do 7500 oil changes on mine all the time, and the oil analysis comes back without any problems.

 

[HarryLui]

Every 3 months is crazy, unless you are using the engine very hard.

Not really "crazy", it would depends on use.

For example, I drive 55 miles a day, at minimal, 3 months would mean over 4000 miles in commute stop and go traffic, plus my car have over 300,000 miles on its turbo engine.

 

[Pacfanweb]

But aren't the surfaces also more sensitive to proper lubrication when tolerances are lower?

Yes, yes they are, that's why cars use "thinner" oil these days. You'd burn a newer engine up if you used some old school 20w50 in it for long.

So it's all relative....as long as you use the correct viscosity oil, everything gets properly lubricated AND you get less blow-by.

I would like to correct one thing, though: The MAIN reason that today's engines have less blow-by than say, engines from 1978, isn't because the tolerances are tighter.

It's because of EFI. Carb'd engines have TONS of blow-by, because they don't meter the fuel as precisely as EFI can. A carb is simply dumping fuel all the time, and there's a fuel/air mixture present in the intake at all times. EFI squirts a precise amount of fuel ONLY when it's needed, and only air flows through the intake.

You could take an engine from today, and convert it to a carburetor, and your oil would be contaminated much faster than with EFI, tighter tolerances and thinner oil be damned.

 

[BUTCH1]

Yes, yes they are, that's why cars use "thinner" oil these days. You'd burn a newer engine up if you used some old school 20w50 in it for long.

So it's all relative....as long as you use the correct viscosity oil, everything gets properly lubricated AND you get less blow-by.

I would like to correct one thing, though: The MAIN reason that today's engines have less blow-by than say, engines from 1978, isn't because the tolerances are tighter.

It's because of EFI. Carb'd engines have TONS of blow-by, because they don't meter the fuel as precisely as EFI can. A carb is simply dumping fuel all the time, and there's a fuel/air mixture present in the intake at all times. EFI squirts a precise amount of fuel ONLY when it's needed, and only air flows through the intake.

You could take an engine from today, and convert it to a carburetor, and your oil would be contaminated much faster than with EFI, tighter tolerances and thinner oil be damned.

One of the issues with carbs is as they got older and more out of whack people just kept driving them until the car started stalling or wouldn't start but all the time they were accumulating sludge and crap in the engine. I think you have blow-by in today's engines too but there's no unburned fuel to contaminate the oil. Hell I remember having to do plugs/points every 12K and I don't miss that at all..

 

[JCH13]

I would like to correct one thing, though: The MAIN reason that today's engines have less blow-by than say, engines from 1978, isn't because the tolerances are tighter.

It's because of EFI. Carb'd engines have TONS of blow-by, because they don't meter the fuel as precisely as EFI can. A carb is simply dumping fuel all the time, and there's a fuel/air mixture present in the intake at all times. EFI squirts a precise amount of fuel ONLY when it's needed, and only air flows through the intake.

You could take an engine from today, and convert it to a carburetor, and your oil would be contaminated much faster than with EFI, tighter tolerances and thinner oil be damned.

Direct injection excluded, there is tons of fuel in an EFI intake manifold, the runners are generally soaked in fuel.

But to play devils advocate, you don't think that in 30+ years there have been any appreciable advances in engine ring design, ring fitment, or crank case ventilation (which mitigates the impact of blow-by gases)?

 

[Jumpem]

Every 3 months is crazy, unless you are using the engine very hard.

I'm at every month and a half right now.

Subaru calls for 3,750 mile intervals, and that is how often I get there. At least on the new models they are calling for 7,500 mile intervals, so I could go three months then.

 

[Bartman39]

Short story that comes to mind about this topic...

My wife told me about her parents buying her a new Camaro in 1981 with a V6 and she loved it for her first car of course... Well a several months went by and one day her dad asked her when she had the oil changed the last time...? Uh her reply was "you have to do that...?" She had almost 40K miles on the car at that point with break-in oil still in it... I asked her just how bad was it and she told me they changed the oil and filter and removed the valve covers to check it also and of course there was gunk all over so it was flushed too... But no bearing issues or burning of oil later either, so figure just luck and she was quite easy on the car...

What I relate to this is the oil life monitors are good no matter what they atleast give someone an idea that they need to get something done and soon... The auto makers would not have them timed to the point of letting the average driver go way past the normal service interval (that they recommend) and the ones that do are just stupid... Those of us that do run our cars & trucks in severe conditions know it so in most cases take better care of the service intervals... A good idea is if you dont know when it was changed last or if there is any doubt change it anyhow as it wont hurt anything and for sure your wallet because an engine cost just a bit more than an oil change...:thumbsup:

 

[Jumpem]

Another note: my Honda dealer actually refused to change the oil on our Fit at earlier intervals. They said to come back when the orange oil change light came on.

 

[LTC8K6]

Another note: my Honda dealer actually refused to change the oil on our Fit at earlier intervals. They said to come back when the orange oil change light came on.

Good dealer. Honda uses a break-in oil that should not be changed too early.

 

[mgttr]

Another note: my Honda dealer actually refused to change the oil on our Fit at earlier intervals. They said to come back when the orange oil change light came on.

The Honda dealer insisted I not change the oil before 7,500 miles on my 2005 Accord. They claimed there was special break-in oil in there that should not be changed out early.

I wonder if any manufacturers other than Honda use some type of break-in oil?

 

[Eli]

Most manufacturers use a break-in oil.

I don't think it matters much. Proper break-in depends on user input, not the oil in the crankcase. The idea that any oil can prevent proper break-in is a myth.

 

[Bartman39]

Most manufacturers use a break-in oil.

I don't think it matters much. Proper break-in depends on user input, not the oil in the crankcase. The idea that any oil can prevent proper break-in is a myth.

Eli... I would got that far...? Synthetic for break-in and diesels dont mix to well... We tried that some time ago with Royal Purple and almost could not get them to stop using oil if it were used for break-in... (7.3 liter Fords) We had to switch them back to reg mineral oils to get them to fully seat the rings and even Ford told us this... As for smaller diesels I cannot say just havent done much with them...

 

[Eli]

Eli... I would got that far...? Synthetic for break-in and diesels dont mix to well... We tried that some time ago with Royal Purple and almost could not get them to stop using oil if it were used for break-in... (7.3 liter Fords) We had to switch them back to reg mineral oils to get them to fully seat the rings and even Ford told us this... As for smaller diesels I cannot say just havent done much with them...

Hmm. That's pretty interesting. Maybe I'm wrong?

It just seems crazy. All that's happening with ring-seat is the shearing of the peaks of the crosshatch. I don't think oil can prevent wear on that level...

 

[Bartman39]

Eli, I think it has more to do with the heat of the engine...? Diesels do not build heat like gasser, also they react different from what I understand... What I`m saying may not be the case now with newer tech but a few years ago with the older 7.3`s Fords we for sure had the problem... I bought my Duramax used with 95K miles on it and switched it to RP but it was of course already broke-in...

But I remember when I did the headgaskets on it there was still alot of crosshatching in bores which struck me real funny...? Had to do the headgaskets due to 44psi boost and stock headbolts & gaskets dont get along to good... But ARP makes a good fix for this along with the newest generation of headgaskets...:thumbsup:

 

[Howard]

Hmm. That's pretty interesting. Maybe I'm wrong?

It just seems crazy. All that's happening with ring-seat is the shearing of the peaks of the crosshatch. I don't think oil can prevent wear on that level...

Perhaps the oil is meant to encourage that.

 

[exar333]

That depends on how you drive your car doesn't it? If you barely ever boost, I think long oil changes are probably OK.

I do 7500 oil changes on mine all the time, and the oil analysis comes back without any problems.

I will find out. Doing my first oil change at 1k and getting an oil analysis done to see what it looked like after the first 1k miles with barely breaking the boost threshold. 7500 is too much for me...more details to come.