Increased oil change intervals


Read and learn.



There are temperature ranges for the SAE ‘weight’ classifications and it is my understanding that a 10W30 oil tests at the upper end of the 10 spec and the lower end of the upper spec. But regardless, oil has seen some vast improvements in recent years. The non detergent 30 weight oils that were common when I was young could become so thick and sludgy that chunks could plug the drain hole on older vehicles with extended service intervals.

It’s hard to argue with results and API-SN oils seem to be worth the cost in real life fleet tests that I have read. I shop around for a good deal but only buy name brand SN oil for late model vehicles. And at 6,000 miles it still looks bright.


My guess is that your “fairly new Toyota” specs synthetic.
It isn’t a marketing ploy. It’s because, as others here have already said, engines run far cleaner than they used to AND oils have improved.

The biggest factors IMHO are that engines are built at the manufacturer to ensure that dimensions remain well within the statistical “normal variation” and not allowed to drift away from the optimal dimensions to the standards they used to be allowed to. This is done by applying sophisticated applied statistics to the manufacturing processes and monitoring and reacting to variation rather than simply dimensions. This has implications beyond just consistence of parts. It also allows analysis of fault cause as well as monitoring of the need for preventative maintenance on the machinery, and adjusting of the machinery maintenance schedules.

Additionally, amazing design software that can predict thermal profiles, stress propagation, finite element analysis, and other technical issues is now ubiquitous… and much of it didn’t exist twenty years ago. This allows design improvements, materials changes, etc. before the first metal chip is cut.

Another biggie is extreme advancements in fuel management. This prevents unburned and incompletely burned gasoline from washing away oil and leaving deposits on valves, pistons, etc. etc. etc. Modern fuel metering systems are light years advanced from where they were twenty years ago.

Even Exhaust Gas Recirculation, which replaces a bit of oxygen in the induction system with spent exhaust gasses, are being eliminated in favor of the new Variable Valve Timing, which also reduces contaminants.

And oil keeps improving.

However, if you feel uncomfortable with going 10,000 miles between changes, as do I, simply change the oil at an interval that you prefer. One objection that I have to 10,000 mile intervals is that far too many people don’t check their oil on the dipstick. And chronically letting it run low will cause premature wear.

My 2005 Toyota (Scion) doesn’t have an OLM. Neither did my 2005 Corolla. It would not surprise me to find out that a lot of cars don’t have OLMs. I wouldn’t trust them anyway. I prefer a dipstick combined with reasonable change intervals.


Using 5-20 oil in place of 10-30 will result in lower oil pressure. Pressure is produced from a combination of factors. In a nutshell, pressure is a result of restriction of flow. The smaller the orifice, the higher the pressure. Yes, I designed fluid pumps. We used to pump silicone. Talk about pressures. A motor that is designed with bearing cleanaces for using 30w oil will never be retroactively cleared for use with 20w. A syn 20w will produce lower pressure than a Dino 30w.


Very interesting

So why would Toyota retroactively publish technical service information . . . long after my car was built . . . saying it was acceptable to use 5w20, versus the 5w30 which is listed in the owner’s manual?

They must figure that at least a few people will follow their updated recommendations


WAG: Maybe Toyota wants to increase the fleet gas mileage by specifying a less viscous oil. All the manufacturers do it for new cars now. I don’t know what that buys them for older cars beyond a small increase in mileage, but there is some logic to this hypothesis.


But here’s where it gets interesting . . .

As far as I know, that updated recommendation isn’t available to the general public, unless you paid to access the technical website

So the average owner of that 10- or 15-year old Toyota probably doesn’t know the manufacturer “okays” the use of 5w20 engine oil, versus what’s listed in the owner’s manual


The best case I have ever seen for using a heavy weight oil was when I was returning from an off campus event with a friend who had a 1950 straight eight Pontiac. We were 35 miles from campus and a connecting rod started knocking. He.nursed the car to an all night service station and had the attendant drain the oil and refill the pan with 90 weight gear lube. The old Pontiac got us back to campus. We all teased the owner about how many miles he would go until the next oil change. We never found out because the next day he sold the car for junk and had it towed away.


Does the average owner of an older Toyota change their own oil? It’s more likely than for a new one, but is it a large percentage? I’d be surprised if anyone kept that statistic.


In 2007 Toyota may not have had a great deal of confidence in the 5W20 oils available at that time.

Many oils did not “stay in grade”. i.e. the viscosity figures did not meet specs at the prescribes temperatures. Way back in 2005 Ford called for 5W20 in some of their cars, to get better mileage for ratings. I was very mistrustful of most mineral oils at that time.

I did not follow Toyota’s advice and have kept using 5W30 since all my driving is low stress.

Consumer Reports years ago tested a number of motor oils and found many did not meet the viscosity specs; the worst being Texaco’s.

In other words, what’s on the can or bottle now usually is correct, but there are still cheap oils that will not meet the viscosity test.


For the record . . .

I’m still using 5w30, as per the owner manual, but I’ve been using full synthetic for awhile now

I change every 5000 miles, when the oil change reminder light turns on. It works out to about every 8-9 months


Good going! There is also a Time Based schedule on older cars, and 8-9 months is about right for your driving. That’s exactly what I do.


My daughter bout a new 2014 Camry in Dec 2013. It came with a 2 year/20k maintenance contract. There is a maintenance required light but it illuminates every 5k miles because it calls for a tire rotation at that miles interval. The recommended oil change interval is 10k or one year with 0w20 synthetic oil.

This is our experience so far. The dealer changed the oil at 10 and 20k. I assume that they used the specified oil. I changed the oil at 25k and used the new Mobil 1 FE 0w20. At 30k, I did another oil change but I used the new Pennzoil Ultra synthetic 0w20. She didn’t bring me the car again until the 40k mark.

When I did this oil change, I noticed a build up of sludge on the inside surfaces of the oil filter cartridge. It wasn’t a lot but it did cause me concern. I didn’t notice this sludge earlier but frankly, I’m not sure I even looked for it, but I usually do clean everything while I have it apart. I wasn’t looking for it this time either but there it was.

I used Mobil 1 FE this time and I told her to bring me the car every 7500 miles from now on. I have always used 7500 mile oil change intervals with synthetic oil in the past dating back to the mid 80’s and have never had a problem, but then all my previous oil filters were spin on. But I never had any sludge accumulate under the valve covers in any of them. None of my cars had less than 150k miles and most went over 200k for me.

I’ll keep watching on future oil changes with this vehicle to see if any more sludge builds up in the filter housing.


@Docnick. I remember the Consumer Reports motor oil test which was some years back. One thing I remember from the article is the same brand of oil of the same viscosity bought in different regions of the country performed differently in CR’s tests. My suspicion is that a refinery may bottle the oil under different labels. I had a relative that worked for a canning company and they canned peaches, for example, under the Hunts Label, the Stokley label and probably other labels. The cans all came down the same line and different labels were applied depending on the order. It wouldn’t surprise me that the oil bottles of say 5W -30 coming from a particular refinery come out with different labels but is the same oil.


I had a friend with a Toyota that never changed the oil in her car. Seriously, she added oil once in a while if it got low but never replaced it. Seemed to work for her, but her car was less than 10 years old. Still, one thing I’m pretty sure of, there’s no penalty in terms of engine life if you error on the side of replacing the oil and filter too soon compared to too late. 5,000 miles is the longest I’d recommend between changes irrespective of the type of oil used.


Good point! The API specs have been tightened up considerably since that time in terms of testing and verification. But no matter how good the specs, individual bottlers can still screw up.

That’s why I would trust Mobil1 and other top brands.

Please also note that Amsol, who claim to have the best oil, has been too cheap to run all the required and expensive API and SAE tests.


most new cars do not burn oil. So a longer oil change interval probably never gets into a low oil level situation. Will a hi mile, 10 yr old car leak and/or burn oil and result in a low oil condition if the owner does not check oil level regularly? What happens to motor if you continually run 1 qt low? Or 2 qts?


As long as the level remains above the pick-up point, everything still gets its dose of oil. But the oil that’s still in there will degrade faster, and the engine may run hotter compared to a full charge of oil in the crankcase.


Yep, the function of oil is not only to lube the engine but also to dissipate heat. So the less oil, the less it will be able to remove the heat from the engine.


I have the oil life monitor in my gm, it has never gone off, regular old dino oil average around 5k mile for oil change, went up to 8 one time due to family stuff, never got prodded by the car for an oil change, 180k or so on the engine now, and no oil consumption to the degree I even need to add 1/4 of a quart, dejavu hope it was not this thread. Apologies if so. :smirk: