Can I uses regular oil vs. synthetic?

Quick lubes may be familiar with cartridge filters, but their factual history of problem free performance is far from stellar.

The owners manual for the Gen 3 Prius sprecifically recommends
0W20 SYNTHETIC oil. Thats for a reason. The engineers who designed and built the ICE and powertrain determined after much
engineering work and testing that it is the best oil to be used for
OPTIMUM performance of the vehicle. And, unknown to most on this forum, the TOYOTA 0W20 SYNTHETIC OIL is the OPTIMUM oil to be used.

It is the lightest of any 0W20 synthetic oil readily available. It is far
lighter than Mobil 1 and it's specs are outstanding. It is especially
superior to ANY conventional 5W20 weight oil. The Viscosity index of the Toyota 0W20 oil is 216, It;s 40C viscosity is 37.38 and it's 100C viscosity is 8.54. Synthetic 5W20 oils have viscosity indexes of 150 to 150 which is far far less than the Toyota 0W20 Synthetic oil, and their 40C viscosities can range from 48 to 50, far higher
than the Toyota 0W20. What this all boils down to is that the Toyota 0W20 is the best possible oil available for the frequent start/stop operation of the Prius hybrid. It is far lighter to reduce friction and make it easier for the ICE to deal with the many start.stops. And since over 80 % of engine wear occurs with cold starts, it does a much better job of helping to insure the longevity of the ICE. Keep in mind that in city driving, with the many start/stops, the ICE will rarely see full operating temperatures.

Prius owners are most definitely NOT "much better off using conventional 5W20 oil." That statement is absurd ! We have never experienced excessive fuel dilution with our Prius operation. Fuel
dilution can possibly occur with only frequent short trips ( 1-5 miles ) but not with a balance of city and expressway operation.

For one to say that the viscosity difference between the Toyota
0W20 oil and conventional 5W20 oil "is mininmal" means the person
knows not of what he speaks !!!

 

IIRC GM recommended 0w30 in temps below 32F for that reason. But a 5W-xx oil is definitely adequate, but possibly not ideal.

Basestocks in conventional oils are more refined than before and have leave fewer deposits than before. The new API SN standards really increased the standards for piston ring cleanliness so I would not be concerned at all unless the engine was turbocharged.

Percentage of PAO is minimal. Arguably most API SN conventional oils now, are a blend to a degree.

Agreed, but as mentioned earlier, many API SN oils now are blends to a degree. It is the only way they will be able to meet the tougher standards. But you are correct-- this is unlikely to be a common retail product.

Agreed.

Fully agree, and that is why I recently purchased 3 cases of Toyota 0W20 SN for myself and will be switching back to it from Mobil 1 0w20. And in theory, the Toyota 0w20 should deliver the best fuel economy for the reasons you mentioned.

True, in theory. Though in practice "much better" is questionable. The 2g Prius's engine cycles on/off just as much and it worked fine with conventional 5W30. Engine wear was not an issue with that engine, and I would not expect it to be with conventional 5W20 either. With that said, the differences between 0w20 and 5w20 are minimal and are unlikely to make any significant differences in real-world use, but Toyota 0w20 is definitely optimal.

Okay, maybe that statement was a bit bolder than I intended. My example was meant to illustrate those situations where the owner drives 4,000 miles a year with mostly short trips. In that situation, an oil service every 6 mo with conventional 5W20 would be the better option than an annual oil change with synthetic 0W20.

Also, fuel dilution is an issue. It is not significant like it is with many direct-injected engines, but search for the UOAs on this site and bobistheoilguy and you will see that in some of the reports that the flashpoint is lowered and viscosity has declined more than expected.

Again, in theory and in real world use is different. There is likely little difference in fuel economy between the two in real-world use. The difference for all but the most enthusiast drivers, will likely be unmeasurable due to variations in fill-ups, driving routes, temps, etc. The engine wear issue is also moot because in most climates the conventional oil is adequate.

However, I do agree that the Toyota 0w20 IS the optimal oil. My earlier post was simply to illustrate that in certain conditions (4k/yr driver) a shorter interval with conventional 5w20 may be more realistic.

 

Congrats on buying the cases of Toyota 0W20. Wise choice !

Not the least bit interested in your "theory vs real life" bullpies.
You can yak that BS until hell freezes over and you still wonl't
know what you're talking about.

Suffice it to say that the Toyota 0w20 oil is the best choice for your Prius !

 

Okay, get this...I call my Toyota dealer to inquire about my 48,000km oil change...they say I need a maintenance package and it will cost $114.00 (Canadian)...so I say, "That's with synthetic oil, right?"...and she is confused and says, let me check...she comes back and says, "No, that's with reg oil, for synthetic oil, if I want it, it will be $50 more..."
At this point, I am a little upset and say, "No, its not, if I want it...It is what is supposed to go in my car...and they should know this!!!
Then I talk to the service manager who says that the last two oil changes have been with regular oil...
Now, I am really upset because everytime I come in for an oil change, at the SAME dealer, I insist on SYNTHETIC oil, and have to tell them repeatedly EVERY time"
Just like this time...when I am reminding them of this on a phone inquiry PRIOR to the appointment...If is something that I MUST mention everytime I call or step foot in this dealership...I feel that it is very important to constantly remind them about...
But, it doesn't seem to matter to them how many times I mention it...they just go and do whatever they want...
There seems to be no communication between the service advisors and the mechanics...
VERY, very frustrating!!!
I have even called Toyota Canada about this and they suggest going to other dealerships but guess what happens when I call them...you got it...totally ignorant of the fact my car requires synthetic...
Should I buy a case of Toyota synthetic oil and bring in my own oil for oil changes?
Anyone in the Toronto, Ontario, (Canada) area had any success with this?

 

Does anyone want to guess/infer the reasons for this recommendation? During normal operation, when a warm ICE is cycling on and off, with oil temperature at perhaps 60C. to 80C., these oils (0W20 and 5W20) have very similar characteristics. So, to me, there is no warm engine issue.

Is the reason administrative, i.e., if you do the EPA test with 0W20 then this must be your oil recommendation?

Is there some issue with really cold starts where the 5W20 does not flow sufficiently through the rather small oil filter element?

Does the GenIII MG1 not like to put out a lot of cranking torque for a really cold start?

Does the VVT require low viscosity during cold starts to function properly?

Anything else?

 

In the end I believe it is best to follow the manufactures recommendation -- the engines are set up to use a certain viscosity and the filters are all designed with this in mind and the intervals.

Some manufacturers use different intervals -- Why does Porsche say it is fine to leave synthetic oil in a low mile car for two years and Toyota says to replace at one year regardless of miles?

Since we will be using this car more than the 10k a year - the synthetic is the way for us to go to extend the interval.

We have to send a lot of our cars to the quick lube places and in 20 years and untold changes - we have never had any issues. My personal cars are a little different and I normally provide the oil and filter and have the service done at my local shop when something else need to be addressed.

 

My guess is that, since the 5W20 can be dino or semi-synthetic oil, they recommend the shorter interval compared to 0W20 which is always full synthetic. Even though the viscosity characteristics may be similar, the aging and other performance characteristics are not.

 

Using the numbers in these posts...
Case A: quick lube every 5K for $30 = $60 for 10K.
Case B: Toyota every 10K for $75.
Even if the numbers are correct, not much difference in cost. $15-20 a year if you drive 12K.
Why not just relax and use Toyota from now on?

 

Case A: quick lube every 5-7k for $42 (market price for conventional here)

Case B: Toyota 0w-20 every 10k for $55-$70. Or major-brand 0w-20 at quick lube for $75.

However, interestingly I've noticed that a good # of the cars I see that have been run on 7-10k intervals on synthetic oil only develop oil leaks later in life. This is purely observation and I do not have any scientific reason as to why this happens.

My friend with a 05 Accord 4-cyl has 155k and he has used Mobil 1, Amsoil and Redline oils from day 1 at 7-10k intervals and he just spent $1200 doing the timing chain case, crank seal, oil pan, VTC o-ring and valve cover gasket due to leaks. I've never heard of that engine family having leaks on cars using conventional at shorter intervals. Go figure.

 

I am not sure what your manual says mine says this on page 552:

Recommended viscosity: SAE 0W-20

SEA 0W-20 is the best choice for good fuel economy and good starting in cold weather.

If SEA 0W-20 is not available SEA 5W-20 may be used. However, it must be replaced with SAE 0W-20 at the next oil change ....

1. SEA 0W-20 is by definition is syntetic (well kind of)

2. According to you 5W-20 per 5000 miles is just fine... maybe maybe not. BUT as per the Toyota Prius manual IT IS NOT....

Of course you choose what you think is better ....

 

I've read all of the post concerning different types of oils, ie 5K vs. 10K etc..... My concern is with the 10K even with a synthetic, what about the filter? I haven't seen anybody mentioning the filter. Those flimsy paper type ones, what do they look like after 10K miles? I just bought a used 2010 Prius with 45K miles. I have a guy here in town that will do my oil changes a lot cheaper than discussed here. I've always went to the dealer and bought my filters. I've driven many higher end cars. I still own an 09 Infiniti. I have never had any problem with any of them. I mentioned this to him yesterday when he was rotating my tires at my 5K interval. He brought up the concern of the filter. I have found in my 40 years of buying cars that most dealers find a way to take advantage of the consumer. I was told by Infiniti not to use synthetic as the valve didn't seat properly, as it was to slick! So I'm thinking of buying the filters from Toyota, and letting my guy take care of my car on 5K intervals. Oil change, tire rotation, new filter, and fluids topped off. I can get 4 done for what the dealer charges me for one. I live in the south and will probably drive my car around 15K per year...............We have some cold weather in the winter, but not near as bad as the northern states...............

 

The filter is there to remove metal particles from the oil and with modern engines could probably be left for 20,000miles. I am not advocating this but how much metal do you think is wearing off your engine in 10,000 miles. It is the oils job to carry any combustion deposits.

If the filter is going to become blocked at such short mileages with modern synthetic oils something is seriously wrong with your engine.

 

TRD (Toyota Racing Design) makes a filter for the Prius that are made with a synthetic media rather then paper media found in the standard Prius filter.
Here's a photo one of the members took showing the stock and TRD filters from this thread
http://priuschat.com/forums/gen-iii-2010-prius-care-maintenance-troubleshooting/76710-how-many-you-insist-trd-oil-filters.html

FWIW- I bought the TRD filters for my 2012 Prius.

 

The Toyota filter is of high quality -- looks nicer then the Mann filters on a Porsche and people leave them in for two years all the time. I order my maintenance items from an online dealer and have them on hand - cheap and easy.

I think once you see how clean the oil is at 6k you will not worry about going out to 10. If it looks dirty you can always change it early.

 

My commute to work is 3.7 miles each way thru city lights. The Toyota schedule calls for the 5K OCI for severe service , one of which being short trips. Would mine fall in this category? Is there a way a UOA at say 7,500 Miles can show if I could actually go with 10K OCI since Toyota doesn't define (that I remember seeing) what a "short trip" is?

Thanks.