Oil change interval for synthetic motor oils

You should check the oil level and make sure it's not low. You can wait longer and just reset the light

 

It depends.
Only way to know for sure is to send a sample to Blackstone Labs.
FWIW:
1) Industry recommends changing every year - even synthetics.
(Reason for yearly is moisture & acidity)
2) Some change every two years - test w/ Blackstone.
3) Every 10K miles is also a "norm" but test to know for sure.
4) Just follow the OEM recommendations
(Some say 5K others 7.5K some even 15K mileages)
(Check your owners manual Toyota maybe every 10K)
That's my 2 cent comment to help answer the question.

 

The maintenance light will come on 6 months or 5000 miles after a reset. It is not a condition-based reminder.

Many manufacturers, including Toyota are now recommending oil changes at 1 year intervals or 10000 miles with synthetic oil. It should be noted that most new Toyotas call for 0W-20 synthetic oil , but the 2nd generation Prius still requires 5W-30 oil with the shorter drain intervals.

I switched to Mobil 1 5W-30 at the fourth oil change, and went to the 10K/annual change after the powertrain warranty expired. My car is low mileage, so almost every change has been made on a time basis rather than by mileage.

 

My Energi just activated this week after its two year or 20k miles interval (plug-ins can go a lot longer due to running in EV mode so much and use full syn) yet I had only traveled 12k miles in that time frame. GM, OTOH, use other metrics besides time/miles to gauge oil longevity and show oil life in percentages on their info screens.

FWIW

 

Just a couple thoughts....

Check the definition of “synthetic”, “semi-syn”, and “conventional”. It will will be muddy and confusing at best. Legally, a group III can be called “full synthetic”. This covers over 90% of the “fully synthetic” labels out there when in fact it’s a highly refined (and usually very good” “Dino” or conventional oil.

If I’m going to spend that kind of money I want a real (IMO) synthetic, a grpIV PAO or V Ester base stock. Now, you will always have a mix of 2-3 base stocks but 70% of the “good stuff” is desirable.

Why do we change our oil? Does the oil “wear out”? Sometimes it will oxidize or thicken from the light ends burning off through your PCV system and getting past the rings. Just as commonly, the additive package gets “used up” and one of the more severe problems is the total base number (TBN) rising enough that acids and other corrosive things from blowby of combustion byproducts can be harmful to the engine and oil. Fuel dilution is another issue. But, even the better GrpIII oils can handle 10k OCIs ok and a boutique “true” syn with its robust base oil and equally robust additive package will laugh at 10k oil changes.

The contaminate load is a big reason for the OCI limits. Look st ATF. Not a lot different than engine oil but it’s normal to go 30k to 150k miles on it. Why? Because there are no acids and water and particulates and other nasty stuff from combustion contaminating it in a transmission. And in a transmission most particulates are large enough that the filter can remove them. The oil filter on an engine is barely needed and basically catches rocks and small animals but not the majority of the contaminates. Dispersants keep the bad stuff in suspension instead of going to the bottom of the pan to be picked up in a higher concentration by the pickup. For what it’s worth the air filter is the most important filter in a car by a mile but that’s a different story. So, we mainly dump the oil to get rid of the contaminate load and also to replenish additives and refresh the base oil. As I said, the last two are less important with the better oils.

A note, the typical $40 Blackstone test is great for seeing how much life is left in the oil; coolant in the oil, additive levels, viscosity, fuel dilution, etc. Very useful. However, the wear metal section is all but worthless. It is not a test for determining engine wear, only oil health. A particle count is the only way to accurately determine the concentration and size of wear metals. The Blackstone tests only show the very small particles, <10 microns if I remember right and it can be argued that it’s the larger ones that are not “seen” that are the result of rapid wear and more damaging wear. Another issue is oxidation will show up as wear metals in the Blackstone tests. This is why Redline oil typically shows poor wear metal results for the first OCI or two. It cleans very well due to its ester base oil and unfortunately the removal of oxidation that’s suspended in the bulk oil is interpreted incorrectly in these cheap tests.

The other factor is the amount of ICE off time vs mileage. An hour meter would be nice and of more value than vehicle mileage.

Of note, I do not believe a 0w20 is possible without at least some synthetic base oil to take care of the cold flow requirements and protect well enough when hot. Even so, the 0w20 vs 5w20 will have a lower HTHS viscosity with all else being equal which makes it less “robust” with HTHSv being directly related to bearing and cylinder/ring wear. While 2.6 HTHS is usually considered the minimum to avoid excessive wear, in my experience a higher value is needed in the vast majority of the cases. One of the many reasons I run redline is the ~3.0 HTHS in their 0w20 and 3.7 for their 5w30 whichbis higher than most 40wt oils. Toyota 0w20 had a 2.6 value last time I checked.

Also, upon startup, as long as you have an oil that’s even remotely appropriate for ambient temps, time to full pressure and lube is usually under 1 second. Farthest from the pump and pan are the cams and the lobes are usually bathed in pools of oil so lube is instant there. Journal bearings use hydrodynamic lubrication where oil pressure as supplies by the pump doesn’t matter and the crank floats on the oil still in the bearing from the last shut down the second it begins to spin and a second later fresh oil is supplied by the pump. Do thinner oil does not mean better lubrication at startup and the system is stabilized in about a second anyway, not seconds and minutes as I’ve seen mentioned. Another good thing about redline is it really likes to stick to metal over long periods of time so no dry starts on the ring pack and cylinders.

Not that it matters but the main thing that got us away from the 3k/3month OCI was fuel injection. Carburetors were an oils worst nightmare. No way to check the AFR except toward the end when they began using narrow band 02 sensors in a crude way. When cold, the choke on usually meant tons of raw fuel washing the lube off of the cylinders and making its way into the pan. The typically rich mixtures killing the oil and causing tons of cylinder/ring wear or the lean mixtures coupled with imprecise ignition timing and no way of monitoring knock did a great job of creating huge pressure spikes in the cylinders, knocking out rod bearings and shearing the oil and sometimes catastrophic engine failure.

Plus, the oilbase stocks of the day wete horrible, wanting to return to its natural state of crude oil sludge just from heat cycling, not to mention the wax buildup for a decade or so, and this was before the carburetor did it’s best to destroy the oil. Between better base stocks and even more importantly, closed loop feedback fuel injection, engine life more than doubled in some tests like the Buick V6 and Chevy 4.3 V6, both of which were originally carbureted and then injected in the later years. Reliability and lifespan literally nearly tripled for both. Even the SFI turbo version of the Buick V6 like I have with over 5x the power of the carbureted 110hp version (3x the power bone stock) is way more reliable with far less wear with almost zero changes or upgrades to the long block.

Any modern oil in a semi modern car will go a lot of miles between oil changes but the really good oils like Redline, Motul, and not as good but still good Mobil One (not all offerings), and others will have to be changed only because of the contaminate load and not because the oil is “used up”.

Not that it matters but I go 20,000+ miles on a mix of Redline 0w40 and 0w20 mostly because I travel 240 miles a day so the engine is fully hot the vast majority of the time and I’m covering a lot more ground per revolution of the engine. Think of it like I’m covering 10’ per engine revolution due to gearing under light load at 65mph while around town the engine may spin 20 times per foot traveled. 20-25,000 miles in 99% highway driving is no worse than 5,000 miles in 99% city. I did the math on a different car or mine and found that the engine spun 6x more revolutions per mile in the city than the highway and it was more heavily loaded on average in the city.

Something to think about, gearing and total engine revolutions, engine revolutions per mile traveled, vs only thinking about mileage.

 

BuickGN, are you Bob the Oil Guy in another life? Where do you get all that information and knowledge. Do you work for Redline? SPILL THE BEANS, dude! Nobody in their right mind is that obsessed about oil!

 

I would stick to the 2nd gen schedule, 5000 miles or 6 months, whichever comes first. Don't switch on the basis of an oil manufacturer's possible claims (or internet hearsay): they're not going to help you out if something goes wrong. The scheduled oil change interval could well be overkill, but there's a lot riding on it.