Synthetics?

There are people experiencing increased oil consumption after switching to synthetic at high mileage. If I were you I won't want to risk. Conventional oil should work fine. Just my 2 cents.

 

Try using 0w20. Mobil 1, Castrol, Valvoline, Pennzoil, etc. The extended oil change interval (10,000, just like Gen III) is the primary motivation to switch to synthetic. There may be an issue with increased oil consumption but this is not common. Since the Prius engine isn't taxed like a pickup truck V6 or V8, other benefits like increased fuel economy will be very subtle. For the vast majority of cars, i.e. ones likely to never go beyond 200,000 miles, the engine will last the lifetime of the car regardless of the type of oil used.

 

Yes I agree with seilerts 100% Changed mine to 0-20 Pennzoil platinum the day I brought her home. Hasn't used a drop of oil in over 13,000 Kilometer's.Hal

 

I know for industrial equipment, depending on application, synthetic oils run a bit cooler. Is it a dramatic difference? Probably not

I use synthetics due to proven cold temp performance, especially at -40 and colder. Next is proven durability

I have never used, and will never use, synthetics based on any fuel economy gain. The gains are very minor. You will be disappointed if you switch to a synthetic just for that reason

 

I wouldn't recommend using 0W-20 viscosity if the car is operated in hot areas (like NV or AZ in the summer.) However, if the car is operated in cold to moderate temp areas, use of that thinner viscosity will result in noticeable mpg improvement, probably 5% or so.

 

^^ I change my oil in autumn and spring, till now using whatever the cheapest 5w-30 synthetic ACEA A1/A5, GF4 on the shelf is available. For 5% mpg increase in the winter though, I'll switch to 0w-20 for the autumn change.

Thanks for the hint

OP: in your shoes I would switch to a good synthetic, but I think it prudent to monitor the oil level say every 3k miles for an exchange or two to be sure the engine is not consuming oil. I think it is quite unlikely you will find a problem, but I do not know how the engine has been treated or your oil change habits up to this point. If you do find a problem, you still might be able to switch over to a 10k interval using the Euro blend of the Castrol 5w-30 synthetic because I gather it is a little more viscous than e.g. Pennzoil or Valvoline synthetic.

 

The made in Germany Castrol Syntec 0W-30 is considered a "thick" 30 at operating temp. Therefore it does not carry the Fuel Economy certification

The reference oil for the fuel economy test is a heavy duty 15W-40. The gains in the test are very minor, no more than 3% on average

 

The problem with the "Synthetic" vs. Dino Oil debate is that it is so huge. Not only in Prius Chat but all over the internet. It's one of those debates where marketing meets fact, and personal opinion meets tradition. And knowledge meets personal empiracal observation and experience...

So if you look for an answer...you'll find all of them...and thus no answer.

Therefore, what I usually recommend, is go ahead and ask, go ahead and research, then do what you are most comfortable doing...what makes you feel best about your automobile.

I personally do like synthetics...because I do believe they are more durable and offer benefits on start up...and in cold tempatures....

But I also believe, that what is more important is dilligent attention to changing your oil when needed. Regardless of whether it is with synthetic or not....

Good Luck...

 

^ Pretty much summed up what I would have said.

 

My little 86 Mazda B2000 pickup with 4 cylinders has 317,000 miles on the block and has just started using a little oil. I've replaced the heads, transmission and driveshaft about 10 years ago, but can't seem to wear the block out. I use Mobil 1 in the PRIUS.

 

Wait, so what did you use for all those miles on the B2000?

- D

 

As far as I know, as long as you don't let the oil level drop below the add mark, there is no risk in using synthetic.

The increased oil consumption that some experience is the result of the oil flowing better past ring gaps or valve seals in a "loose" engine. The engine itself is not changed or damaged by synthetic, and changing back to the previous oil will restore the previous amount of oil consumption with no harm done.

My personal experience using Mobil 1 0W-30 Fuel Economy since the first scheduled oil change in my 2007 Prius with 73k miles and extended oil change intervals has been good. Oil consumption has been almost unmeasurable, and used oil analysis has confirmed that the oil is still good at the end of the extended oil change interval for my operating conditions.

 

Here is a post from a reputable member that says the contrary:

http://priuschat.com/forums/gen-ii-...97-change-synthetic-oil-100k.html#post1146514

Maybe these are rare examples but they do represent some level of risk to be considered.

Do you have experience switching to synthetic at high mileage?

 

I agree, the first time through you should check the level at each gas fill-up, just like in the old days, particularly if trying 0W20 in a hot climate. But it is not as if synthetic will dissolve all of the seals in these engines.

What is your oil change interval? Thanks.

 

Mobil 1!

Really folks, if you do start using synthetics with high mileage engines its going to go in and start doing some serious cleaning of the engine, sludge buildup, etc. Also synthetic flows so well don't be surprised if it starts moving past the oil rings and the engine starts consuming a little oil. Sometimes moving up to a little thicker oil will do the trick to slow down oil consumption. For instance I do a mix of Mobil 1 synthetic 10w30 with 10w40 (in the Mazda truck). Not great performance\economy in cold weather but it slows oil consumption.

 

That second tale involves changing oil grade, not changing from mineral to synthetic. If any conclusion is to be drawn from that one it is to beware that 0W20 may not protect as well as 5W30 in warmer climates.

 

No difference between 5-20 and 0-20 in hot climate. The high # is the same in both oil's. Both will give the same service in high temps! In very hot temps 0-30 or 5-30 may give better protection? Todays high tech. engines will probably like 0-20 blends better. Honda thinks that is the case as they recommend 0-20 in all their auto's . Hal

 

And there's the fact that not all synthetics are lab produced synthetics ....

Some synthetics (type III or IV IIRC) are actually highly refined crude (dino) oil. IIRC, it was Castol that won the right years ago to call Syntec a synthetic oil.

Then there are the Ester based and PAO (sp?) synthetics which are not derived from crude at all.

One can go on and on about it. I prefer the proper weight and type spec'd for the car, keeping up with change interval, regular level checks.

side note - there's always motorcyclists who ask about using car oil in their motorcycle. Problem is, if engine and transmission share same oil, car oil is Not designed for that. Not wise to be a backyard mechanic and not know what one is doing.

Then, there's the ones who say 'oil is oil' just put some in ....... wrong Mr. Engineer.

 

Yes, that is the conclusion that I formed, at least for 2G Prius. My 2004 has 116K miles now and is consuming 5W-30 synthetic oil at the rate of at least 1 quart per 9K miles. (I observe 7.5K mile change intervals.)