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I am expecting delivery of a 2006 Pri in the begining of Jan. I have been reading the threads here regarding the different engine oils owners are using. I have seen everything from regular oil to Mobil 1 synthetic.

What is recomended by Toyota? Will using sythetics void any warranties?
What are the advantages to synthetics, since I have not used them in any of my previous cars? What have all of you found to be any mileage benefits from the different oils, if any?

Your help in understanding this is appreciated.

Greg
 

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webguy said:
I am expecting delivery of a 2006 Pri in the begining of Jan. I have been reading the threads here regarding the different engine oils owners are using. I have seen everything from regular oil to Mobil 1 synthetic.

What is recomended by Toyota? Will using sythetics void any warranties?
What are the advantages to synthetics, since I have not used them in any of my previous cars? What have all of you found to be any mileage benefits from the different oils, if any?

Your help in understanding this is appreciated.

Greg
The benefit of using synthetic is your NOT using oil.
 

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Well, considering that the warranty requires you to change the oil at 5K intervals, no matter what oil you use, I don't see the benefit of using synthetic except maybe in very cold climates.

Someone mentioned that synthetics are derived from oil, so I am not so sure in the long run that you aren't using oil.

Toyota requires 5w-30 oil. If 10w-30 gets put in, you can wait until your next change to put in 5w-30.
 

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I think the overall value of synthetics in a vehicle like the Prius is the quantity of detergents as compared to non-synth oils. The more detergents, or the better those detergents are able to trap soot and other impurities and retain them in the oil until they are changed out is what makes synth oils better than conventional oils. Synth oil might be overkill on the Prius, however overkill with a quality lubricant like Mobil1 shouldn't cause any problems with the Prius.
 

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re: oil

That said, what does the dealer use in the initial oil change? Do they use a low-grade, bulk-rate oil like Jiffy Lube? Or, do they put something in of high quality? (Or, all all dealerships different?) What's the best way to supervise this process?

marlowe
 

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First off, you can see what they use by buying a quart from their service dept. After they change the oil the first time, check the quantity on the dipstick and see if it is at the same indication it was when you bought the car. (usually, slightly above the full mark wich is notched at 3.9 qts.) It seems that the factory ships the cars with 4 qts indicating and Toyota service will continue to do so unless you specifically request something different. You'll get a lot of different opinions here about quantity. It's become a "personal thing"
Toyota uses a standard oil (not synthetic) Weight determined according to local climate conditions but all in the owners manual and what you expect to see. In the dealers personal info kit (quite often advertised on "E" bay) there are some statements that a heavier than prescribed oil will cut down on milage figures slightly while the change to synthetic after a few thousand miles will increase milage figures slightly. Probably not enough to make it a cost saving commodity.
Again, oil is a personal thing and the Prius engine doesn't need anything extra special in it's oil treatment
 

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3.9 quarts is WAY too much. My dealer FINALLY did what I specified, which is 3.5 quarts, and it reads about a cup (8 oz) short of full, which is about .25 quarts. So full would be 3.75 quarts.

My dealer uses Quaker State dino oil for their standard (non-synthetic) service.
 

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DanMan, you continue to completely ignore the value of oil quantity for engine cooling. I'm surprised account of the climate you live in but I would never suggest to anyone to ignore their owners manual. There are just as many folks who believe a little more is better than a little less. The reasoning that 1/10th of a quart of oil, would cut down on your milage is ludicrous. I have never read in any publication concerning the Prius anything other than full oil quantity is 3.9 qts. (2004 Owners Manual, pages 206,283, and 312) And I would also expect Genuine Toyota Service feels the same.
 

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one cup is not going to matter with cooling. Even 3 quarts puts it half way between Add and Full, and that will cool it fine too.

If you are wanting empirical proof 8 oz over full versus 8 oz below full will not change mileage, do you have empirical proof that it matters in cooling?
 

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Nope, I only know that in the higher performance engines before you get to the oil coolers you increase the size of the oil pans for more oil thus more cooling. When you can keep it out of the overhead valves more is best for cooling. 3.5 and even 3.9 is pushing the envelope. It is so unimportant that's probably why the cars are all initially serviced with four quarts. My Jags all had 14 quart sumps in lieu of an oil cooler.
 

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ok guys. after break in or somewhere around 1000miles just for safety , start using mobil 1 and then FAGETABOUT IT! change every 5000 miles ( just started doing that after 40 yrs of 3000 mile intervals)dont worry just just do it . 8) :lol: 8)
 

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ps for my main man dan. i agree that nowadays any ole oil is very good but for me mobil 1 thats the ticket. 8) 8)
 

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very good response hyperion. i have to say tho that unless its a collector car "out of warranty out of here!" 8)
 

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hyperion said:
Nope, I only know that in the higher performance engines before you get to the oil coolers you increase the size of the oil pans for more oil thus more cooling. When you can keep it out of the overhead valves more is best for cooling. 3.5 and even 3.9 is pushing the envelope. It is so unimportant that's probably why the cars are all initially serviced with four quarts. My Jags all had 14 quart sumps in lieu of an oil cooler.
Well, this isn't a performance engine, and it doesn't need a big oil pan. if the oil level were that critical, the add and full marks would be much closer together. As I see it, the two marks are at least a quart apart.
 

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Does anyone have any actual data on MPG vs. oil level?

Is there an oil pressure difference when the engine has 3.5 quarts vs 3.9 quarts? Is 3.9 quarts truly considered overfilling?

If more oil means more cooling, could an increase in MPG with less oil be a result of *less* cooling and therefore less ICE running just to maintain operating temperature? I would expect a measurable reduction in warmup time (although probably very slight) given less oil to heat up.
 

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I do not subscribe to the claim that more oil means cooler oil. Of course at the extremes this is true, but over a small range, it is not significant. Larger sumps have more surface area to provide radiative cooling, and typically also have yubes running through for even more surface area.

An extreme example is the air-cooled Volkswagen. The oil did a large part of the engine cooling (via its oil cooler and finned cast-in sump), not just the air. Oil temps are much higher in this car. The bolt-on deep sump pans have extra fins and more importantly, a improves pickup geometry so the car doesn't starve on hard cornering or during high cornering angles (like in a baja bug).

Both the factory and author John Muir (not the naturalist, though a relative) argued that the extra oil only meant it took longer to warm up in the morning (thereby increasing engine wear, by the way), but reached the same eventual temperature, despite the addition of 2-3 more quarts (up from 2.6 qts, a huge percentage increase).

I can't see a 10-15% increase in oil making a measurable difference one up to normal operating temperature.
 

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Of course it cools the engine. My point is that more oil doesn't mean cooler oil, at least within reasonable bounds. Sure, 1 quart isn't going to cut it, and 5,000 barrels wil never get too hot. But the fraction of a quart we are debating here is not a factor in engine temperature.
 

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Common sense would be that more quantity would provide more cooling. That was the main reason JC Whitney sold so many high oil capacity, finned, aluminum cast, oil pans. Better refined oils along with additives have allowed engines to successfully run hotter and still get adequate lubrication. But 3.9 qts. is pretty close to bottom line for a 1 1/2 Litre engine. I'm sure that's why Toyota regularly services with four qts.
 
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