Help with Oil Choice: Toyota, Mobil 1, Amsoil, or Other?

I would use either Toyota's own 0w20 or Mobil 1 0w20 in that order, both are good for 10,000miles oil change intervals and are the normal Toyota service interval in the UK and Europe.

The Toyota oil has a better specification than the Mobil 1.

Any good quality filter will be fine.

 

I'd use the oil weight and the mileage interval recommended in the owners manual.

 

I would use Mobil 1 0W-30 if weather is cold, otherwise use 5W-30 Mobil-1, you should use factory oil filter on the safe side. Amsoil is quite expensive and hard to get to, Mobil-1 you can buy them at Walmart 5 quarts jug. I bought them for my Prius, they even have the 0W-20 Mobil 1 in 5 quarts jug.

 

Toyota recommend 0w20 for the Prius from 2004 on see Toyota's chart below.

 

I'd rather stick to the required oil weight, I saw that PDF and have tried using 5W-20 on my 2006 Sienna Limited which required 5W-30, once changed to 5W-20 the engine run super duper smooth...but it lose the torque, gas mileage stay the same as 5W-30. Once I drained out the 5W-20 and replace with 5W-30, the low end torque comes back and it coast much better than the 5W-20 oil weight.

 

Took me a while to understand how to read the chart from the legend LOL

Recc says any of 0w-20, 5w-20 or 5w-30 is ok ---- in general

OP: General advice on most cars run on conventional oil for 100k miles is not to switch to a thin synthetic, because of the risk of oil leaks. However, the Prius has such an easy life you may be ok. In your shoes I would try it with 0w-20 Toyota Synthetic, but you *have* to keep a close eye on the oil dipstick for the first year. I would err on the safe side, and check every time I refueled. If I lost more than a quart in 5000 miles I would switch to 5w-30 synthetic.

Avoid the error of only checking for a month or two. Leaks start once previous deposit buildup is removed by the synthetic. As for change intervals, brave people change once yearly. I change every 10k miles or 6 months, whichever comes first. I suggest you err on the side of caution since you are starting with a 100k mile car.

 

With due respect the Prius is not a Sienna. The Prius engine starts and stops much more than any normal engine, and it's design being an Atkinson cycle not an Otto cycle precludes it from having any low end torque. It is also required to have a low viscosity oil especially in cold climates or a DTC may be logged giving engine failed to start. This information is in the hand book.

The lower viscosity oil also circulates faster giving better protection than thicker oils. The lower viscosity oil also does improve fuel consumption in a Prius especially in the 2010 version putting in 5w30 can increase fuel consumption by more than 10% ask Grumpy Cabby.

 

Certain of the Amsoi oils are very good. Others are fairly standard. Often it can be hard to get. Too often it can cost more than other good oils that you don't have to seek to find.

The Toyota oils are good. The Mobil oils are, too. If you have an easy drive to a nearby Toyota dealer to get oil, if the price is good it would be a reasonable purchase.

For 5k mile changes, the Mobil EP would be fine. If you want to go to 10k mile intervals the M1 oils or the Toyota oils would do fine.

You should have no problems going to a synthetic oil even at this late date. The engine is well built and if it is clean and dry now it should remain so. If, by chance, it should begin to weep or seep, you can always go back to conventional oil. I've had good luck switching to synthetics at all mileages if the engine has been tight and dry already.

As for the mpgs between oil weights, that would be up to you to try. It's easy to get a little better mpgs by using a lower weight oil - 20w vs 30w. If the manufacturer suggests it to be a good idea, so much the better. You MAY, however, see differences with a 20w. There may be more noise from the engine. It shouldn't be a problem, just thinner oil with less sound dampening. There may be more oil consumption. Perhaps, perhaps not. Some oils will consume more in some cars than others, and some cars will consume more/less with different oils. Keep an eye on your dipstick, if you'll pardon the expression.

An engine that was originally spec'd for 5w-30 is not going to go wrong staying with 5w-30. Don't be browbeaten for not going to a 0w-20 or 5w-20 oil. But, if you wish to try it, go right ahead.

If you wish to go synthetic, I've enjoyed the service of Mobil 1 and Pennzoil Platinum. Either will go 1 year between changes and 7k-10k miles with no problem. I use Purolator filters and have had good luck with them. The cold you'll see in Indiana isn't far different than here in Omaha. I've never had any problems with 30w's in the winter. If you wish you could try a 0w-30 if you feel a need. Real-world, it's not a truly big deal until you get way below zero.

Comparing Xw-20s with Xw-30s, you could probably better your mpgs just as well by inflating your tires 2-3 lbs higher.

Good luck with your new purchase. It should still have a long and useful service life.

 

Thank you for re-posting that interesting Chart, I made a copy of it this time. However the chart is somewhat in conflict with the USA Prius Gen-2 op manual which calls for 5W-30 (for 2006 anyways). Do not think we have official Toyota guidance on how to interpret the chart. My interpretation is the users op manual for USA region and USA Prius version is the reference.

My personal choice is the same as Nedear88: I use Mobil-1 0W-30 in winter for better MPG and Mobil-1 5w-30 extended drain in summer. Just made the switch.

Now then if you want to be on the highest MPG you might experiment with 20 weight oils especially in winter. But my subjective feeling is the 30 weight gets diluted with fuel so I'd rather stick with that. Better approaches for +MPG include blocking grills in winter, tire pressure as noted, and hypermiling skills.

 

I believe that that staying with a grade or make of oil you are comfortable with is probably the thing to do, but by putting out our results we give other people more information.

I do not think 0w20 was available in the US in 2006 but according to my 2008 handbook it is the preferred choice.

I have used 0w20 from the first and every oil change in my 2008 Prius with one exception when one dealer put in 5w30 even though I had requested 0w20, my fuel consumption went up by 3MPG. The dealer acknowledged the mistake and changed the oil for 0w20 and my better MPG returned.

My Prius is now approaching 83,000miles with no measurable oil used between 10,000mile changes "UK and European recommended interval".

Fuel dilution should not really be a concern unless you do lots of cold starts, and short runs so that any fuel finding it's way into the oil cannot evaporate off.

It is difficult for us on this side of the pond to understand the reluctance of some in the USA to move from 3,000 and 5,000mile oil changes to 10,000miles, when that has been the norm hear for more than twenty years. Many manufacturers are now going to 15,000/20,000mile intervals.

John.

 

Pearl ran on Mobil 1 5W30 for the last five years, in very cold Edmonton Alberta. No problems with starting or stopping the engine (heavy oils can cause it to miss the stop point - the engine is stopped at a certain crank angle and will "go around" if it misses until it gets there).

On previous cars I got better fuel economy with Mobil 1, but with Pearl didn't notice any change.

I -suspect- the Toyota oil will be very expensive. You can get Mobil 1 at a good price from several different suppliers.

As far as extending the change interval, that's up to you to determine. I'd advise getting the oil analyzed during the first year at least once in the middle of the run, just to be safe. The oil doesn't fail, the additives are used up. They resist corrosion etc.

 

Toyota 0W20 is comparable, if not cheaper than, M1 or AMSoil, at least in the US. Canada might be different. Evidence so far suggests that Toyota 0W20 is quite good.

Owner's manuals are full of propaganda and admonishment to use only OEM parts, supplies, and service centers. In many cases there are cheaper and better options, which needn't be rejected out of hand because the book says otherwise.

 

I don't think you could really go wrong with either one, provided you follow the recommended change intervals and use the proper weight oil. At that point, I'd look for which ever may be most cost effective.

I've run Amsoil SSO in my 2010 since the first oil change. I plan to move to their OE one, and it can be had for under $5/qt (plus shipping) for the preferred members online.

 

The Mobil extended filter would be fine, but any good quality filter should also be ok. The amount of particles collected by the filter is actually very small if it was not so engines would not last and there are reports of engines going as high as 1,000,000miles (rare) but 300,000/500,000 miles are known on this forum.